1. 1987. Impact of intensive forestry practices on net stand
values in British
Columbia. B.C. Ministry of Forests FRDA-Report 014. 109
p.
Keywords: release treatments
fertilization
thinning
yield
economics
Abstract: Yield
responses to major silvicultural treatments (regeneration method, brushing and
weeding, spacing and thinning and fertilizer use) are analysed in relation to
growth and yield theory, and their translation into operational use of
treatments to increase merchantable vol. is considered. Data from coastal
Douglas fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla) and
western hemlock/Abies amabilis stands and interior white spruce (Picea glauca),
lodgepole pine (Pinus contorta) and wet belt Douglas fir stands are used to
quantify the net present value of treatments in terms of improvement in net
stand values and merchantable vol. Potentially viable treatment options are
identified for each stand type present.
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2. Bailey, J.D. and J.C. Tappeiner.
1998. Effects of thinning on structural development in 40- to 100-year-old
Douglas-fir stands in western Oregon. Forest-Ecology-and-Management 108(1/2): 99-113.
Keywords: thinning
commercial thinning
regeneration
tree morphology
Abstract: The
composition and structure of the understorey was studied in thinned and
unthinned Douglas fir/western hemlock (Pseudotsuga menziesii/Tsuga
heterophylla) stands on 32 sites in western Oregon. These stands had regenerated naturally after timber was
harvested between 1880 and 1940; they were thinned between 1969 and 1984.
Commercially thinned stands had 8-60% of their volume removed 10-24 yr before
the study (in 1993-95). Undisturbed old-growth Douglas fir stands were present
for comparison on 20 of these paired sites. Conifer regeneration density and
frequency were consistently greater in thinned than unthinned stands. For
example, average seedling density in thinned stands (1433/ha) was significantly
greater than in unthinned stands (233/ha), but very similar to that in
old-growth stands (1010/ha). Seedling density and frequency were strongly
related to the volume removed and to stand density index (and other measures of
overstorey density) just after thinning. In thinned stands, the density of
small trees (intermediate crown class overstorey trees and advanced
regeneration) was 159/ha, significantly greater than in unthinned stands
(90/ha), but not significantly different from that of old-growth (204/ha). The
live crown ratio of these trees in thinned stands (66%) was greater than in
unthinned (44%) and old-growth (48%) stands. Cover and stem density of shrubs
was variable in all 3 stand types. There was significantly less tall shrub
cover in unthinned stands than in either thinned or old-growth stands, which
did not differ. Thinned stands had the most low shrub cover. Salal (Gaultheria
shallon) and bracken fern (Pteridium aquilinum) cover was greater in thinned
stands than in the other stand types, but there was no difference in sword fern
(Polystichum munitum) and Oregongrape [Berberis nervosa] cover. Leaf area index
in thinned stands (6.6) was not significantly different from that in unthinned
(6.8) and old-growth stands (7.1); however, there was more leaf area in shrubs
in the thinned stands. Thinning young Douglas-fir stands will hasten the
development of multistorey stands by recruitment of conifer regeneration in the
understorey as well as by enabling the survival of small overstorey trees and
growth of advanced understorey regeneration. Thinning will also help develop
the shrub layer by increasing tall shrub stem density and cover of some low
shrubs.
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3. Barbour, R.J., S. Johnston,
J.P. Hayes and G.F. Tucker. 1997. Simulated stand characteristics and wood
product yields from Douglas-fir plantations managed for ecosystem objectives.
Forest-Ecology-and-Management 91(2/3): 205-219.
Keywords: thinning
yield
wood quality
Abstract:
Hundreds of thousands of hectares of Douglas fir (Pseudotsuga menziesii)
plantations in coastal forests in the US Pacific Northwest have been
established over the past 40 years. Density management regimes designed to
increase structural and compositional diversity in these plantations are being
tested and implemented on an operational scale, in order to satisfy goals of
ecosystem management. These regimes are designed to promote various tree and stand characteristics, such as trees with large
limbs, stands with multi-layered canopies, and dense unthinned patches. Changes
in forest management policy associated with these types of regimes raise
questions about whether it is possible to manage for both ecosystem values and
timber production. State-of-the-art growth models were used to simulate stand
development and wood product yields under several silvicultural prescriptions.
The results indicated that timing and intensity of early thinnings are critical
in determining both stand structure and wood quality. It is concluded that it
should be possible to manage Douglas fir plantations to provide a high degree
of structural diversity, and wood products with a quality similar to that grown
in many industrial plantations.
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4. Barbour, R.J. and D.L. Parry.
2001. Log and lumber grades as indicators of wood quality in 20- to
100-year-old Douglas-fir trees from thinned and unthinned stands. Pacific-Northwest-Research-Station,-USDA-Forest-Service General-Technical-Report
PNW-GTR-510. 22 p.
Keywords: thinning
commercial thinning
wood quality
Abstract: This
report examines the differences in wood characteristics found in coastal Pacific Northwest Douglas-fir (Pseudotsuga mensziesii) trees harvested at
the age of 70 to 100 years old or at the age of 40 to 60 years from a trial
involving multiple thinnings in Seattle, Washington, USA. Comparisons of differences in domestic log grades suggest
that the proportion of log volume in the higher grades (Special Mill and No. 2
Sawmill) increased with both stand age and tree size. Simulation of lumber
grade yields based on log characteristics suggests that yields of higher grades
of lumber increased until about age 60 to 70, and then levelled off over the
rest of the age range examined in this analysis. We included structural lumber
products in the analysis but not higher value appearance grade products, and
some evidence suggests that yields of these products might have begun to
increase in the oldest trees. The analysis also showed that the younger trees
had larger branches and more juvenile wood, possibly because they had been
grown in stands that received a higher level of early stand management than the
older trees. If these young trees were grown to the ages of 70 to 100, they
likely would not produce the same log and lumber grade yields found in the
older trees we examined.
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5. Barclay, H., H. Brix and C.R.
Layton. 1982. Fertilization and thinning effects on a Douglas-fir ecosystem at Shawnigan Lake: 9 year growth response. Pacific-Forestry-Centre,
Canadian-Forest-Service Information-Report BC-X-238. 35
p.
Keywords: fertilization
thinning
growth
Abstract: Further
results are given for a trial established in 1970 in a 24-yr-old stand in British Columbia, last measured 6 yr after treatment. Volume increments
over 9 yr for heavy thinning alone, heavy fertilizer (urea) treatment alone, or
both together, were 46%, 75% and 120%, respectively.
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6. Barclay, H.J. and H. Brix. 1984.
Effects of urea and ammonium nitrate fertilizer on growth of a young thinned
and unthinned Douglas-fir stand. Canadian-Journal-of-Forest-Research 14(6):
952-955.
Keywords: fertilization
thinning
growth
tree physiology
tree/stand health
Abstract: The
effects were studied of 2 sources of nitrogen fertilizer applied at rates of
224 and 448 kg/ha N on growth of thinned and unthinned plots established in
1970 in a 24-yr-old stand on southern Vancouver Is., British Columbia. Ammonium nitrate yielded higher growth of diam. and vol.
than urea over a 9-yr period, particularly with thinning. Ht. growth was not
affected by nitrogen source. The efficiency of nitrogen fertilizing in terms of
stem vol. response per kilogram of nitrogen applied was greatest with ammonium
nitrate in thinned plots. Tree mortality increased substantially with
fertilizing for both sources, and decreased markedly with thinning.
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7. Barclay, H.J. and H. Brix. 1985a.
Effects of high levels of fertilization with urea on growth of thinned and
unthinned Douglas-fir stands. Canadian-Journal-of-Forest-Research 15(4):
730-733.
Keywords: fertilization
thinning
growth
tree physiology
tree/stand health
Abstract: Diameter
height and volume growth were documented for 9 yr after thinning and
fertilizing in a 24-yr-old stand on a poor site on southern Vancouver Is. The
treatments involved 3 thinning treatments (0, 1/3, and 2/3 b.a.
removed) and 6 fertilizer treatments (0-1344 kg/ha N) with urea. Increments for
both diameter and gross volume increased with the rate of fertilizer
application and responses were still apparent 9 yr after treatment. For
unthinned plots, the 9-yr volume growth responses were 30, 50, and 80% with
fertilizer rates of 224, 448, and 896 kg/ha N, respectively. The efficiency of
fertilizer use, measured as stem volume response per unit of nitrogen applied,
decreased with rate of fertilizer application, but this result may change over
a longer response period. There was a positive interaction between fertilizing
and thinning such that high amounts of both mutually enhanced growth. Mortality
increased with fertilizing, but only noticeably in unthinned plots.
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8. Barclay, H.J. and H. Brix. 1985b.
Fertilization and thinning effects on a Douglas-fir ecosystem at Shawnigan Lake: 12-year growth response. Pacific-Forestry-Centre,
Canadian-Forest-Service Information-Report BC-X-271. 34
p.
Keywords: fertilization
thinning
growth
Abstract: [See FA
45, 2316] Further results are given from the study
established in 1970 in a 24-yr-old stand in British Columbia. Fertilizers (urea) and thinning both increased vol. increments
over 12 yr. Refertilization 9 yr after initial treatment has produced
substantial increases in vol. increment.
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9. Barclay, H.J. and C.R. Layton.
1990. Growth and mortality in managed Douglas fir: relation to a competition
index. Forest-Ecology-and-Management 36(2-4): 187-204.
Keywords: fertilization
thinning
growth
tree/stand health
Abstract: Twelve-year
increments of diameter at breast height (DBH), height, and volume in thinned
and fertilized 45-year-old Douglas fir (Pseudotsuga menziesii) stands on
Vancouver Island, Canada, were related (by regression) to degree of thinning,
amount of fertilizer (3x3 factorial), initial DBH, and a competitive stress
index (CSI). The ability of the CSI to predict growth after treatment was
examined. Causes of tree death, and CSI data, are presented, and the
relationship between them discussed. The CSI was found to be only moderately
good at predicting Douglas fir growth and mortality: initial DBH provided a
better predictor. Most mortality in unthinned plots resulted from suppression,
and correlated reasonably well with CSI; mortality in thinned plots was not
correlated with CSI, and resulted principally from snow damage. Tree height
variability generally became less over the 12 years following treatment, which
is more consistent with two-sided than one-sided competition predictions, a
result which is contrasted to that of many other species.
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10. Barclay, H.J., P.C. Pang and
D.F.W. Pollard. 1986. Aboveground biomass distribution within trees and stands
in thinned and fertilized Douglas-fir. Canadian-Journal-of-Forest-Research
16(3): 438-442.
Keywords: fertilization
thinning
carbon allocation
Abstract: Nine years
after heavy thinning and fertilization with urea, 34-yr-old Douglas firs at Shawnigan Lake (British Columbia) were destructively sampled. Dry wt. of seven aboveground
components (wood, bark, dead branches, new or old foliage, new twigs and live
branches) were determined and regression equations from d.b.h. were developed.
Differences among treatments were shown for all biomass components and for the
proportion of the total biomass allocated to each component. Thinning reduced
the proportion of wood, bark and dead branches while increasing the proportion
of foliage and live branches. Fertilization increased the proportion of
branches but had negligible effects on the proportions of other components.
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11. Barclay, H.J. and J.A. Trofymow.
2000. Relationship of readings from the LI-COR canopy analyzer to total
one-sided leaf area index and stand structure in immature Douglas-fir.
Forest-Ecology-and-Management 132(2/3): 121-126.
Keywords: fertilization
thinning
tree morphology
Abstract: Estimation
of leaf area is important in predicting potential growth. This estimation is
often done by means of a photometer, such as the LI-COR plant canopy analyser,
but such instruments generally give biased estimates. Consequently, conversion
factors are required to convert output from the photometer to the actual leaf
area index (LAI). Foliar biomass was estimated in a 52-year-old Douglas fir
(Pseudotsuga menziesii) stand at Shawnigan in British Columbia, Canada, which had been treated with 3 levels of thinning and 3
levels of fertilizer 28 years previously. The 4 treatment extremes (no thinning
or fertilizing, no thinning and heavy fertilizing (448 kg N/ha as urea), heavy
thinning (to 1/3 basal area) and no fertilizing, and heavy thinning and heavy
fertilizing) were sampled for foliage. Projected leaf areas were calculated
from these biomass samples using specific leaf areas derived in a previous
biomass sampling. Total one-sided leaf area was then computed by dividing the
projected leaf areas by 0.9 to allow for lateral leaf curvature. In addition,
LAI-2000 readings were taken in the same plots and then factors were derived to
convert LAI-2000 readings to total one-sided LAI. These conversion factors were
found to vary strongly with quadratic mean diameter, stand density, mean
diameter at breast height, mean height and stand basal area. The effect of live
crown height was minimal. These should allow the prediction of the conversion
factor based on 2 or 3 of these highly correlated factors.
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12. Beddows, D. 2002.
Levels-of-growing-stock cooperative study in Douglas-fir: Report No. 16 - Sayward Forest and Shawnigan Lake. Pacific-Forestry-Centre,
Canadian-Forest-Service Information-Report BC-X-393. viii
+ 67 p.
Keywords: thinning
growth
tree morphology
Abstract: Results
from the two levels-of-growing-stock installations at Sayward Forest and Shawnigan Lake on Vancouver Island, British
Columbia, Canada, are summarized. Volume growth at both the site-III Sayward
Forest installation to age 51 and the site-IV Shawnigan Lake installation to age 52 has been strongly related to level
of growing stock. Basal area growth followed a similar, though weaker, trend.
Thinning has affected stand development through tree size distribution and live
crown development. Periodic annual increments in volume at both installations
are still two to three times the mean annual increment, indicating the
potential for productivity gains as the treated stands age. Results to date
from both installations are similar to results from other cooperative
installations, generally differing from the more productive sites only in the
rate and degree of response associated with a lower site quality.
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13. Bettinger, P., K.A. Bettinger and
K. Boston. 1998. Correlation among spatial and non-spatial variables describing
a cut-to-length thinning site in the Pacific Northwest, USA. Forest-Ecology-and-Management 104(1/3): 139-149.
Keywords: thinning
commercial thinning
tree/stand health
Abstract: Variables
describing the pre- and post-logging conditions of a thinning site in 47-yr-old
naturally regenerated stand of second-growth Douglas fir (Pseudotsuga
menziesii) and western hemlock (Tsuga heterophylla) in western Oregon, were
examined for correlation, and subsequently used to develop models to estimate
residual stand damage levels. A cut-to-length harvesting system was utilized to
perform the thinning operation, which used a single-grip harvester and a
forwarder, and marked logging trails. Several of the variables were measured in
an intensive field survey; other variables were developed using geographic
information system (GIS) processes. An analysis of correlations among the site
variables showed several obvious, and a few interesting, results that describe
the operation. Most of the variables provided negative, or inconclusive,
assistance in describing the variation in stand damage levels. Only one
variable, the number of original trees/hectare, was significantly correlated
with residual stand damage levels, and was represented in the models that were
developed to estimate residual stand damage levels. The resulting models are of
limited practical value, however, since they explain little of the variability
in damage levels. Most of the variation in residual stand damage levels may
well be explained by random chance, operator error, other
unmeasured operational variables associated with this harvesting system, or
interactions among variables. The main conclusion from the study is that
although both spatial and non-spatial data were utilized in describing the
logging operation and in developing models to estimate stand damage levels, the
importance of using spatial data was inconclusive.
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14. Bettinger, P. and L.D. Kellogg.
1993. Residual stand damage from cut-to-length thinning of second-growth timber
in the Cascade Range of western Oregon. Forest-Products-Journal 43(11/12): 59-64.
Keywords: thinning
commercial thinning
tree/stand health
Abstract: Residual
stand damage was measured on 25% of an area that had been thinned with a
cut-to-length logging system. Total damage (scar area) per acre was less than
in any similar study in the Pacific
Northwest, although 39.8% of the
residual trees sustained some damage. Only 0.8% of the trees, however,
sustained significant damage. Western hemlock (Tsuga heterophylla) was more
susceptible to damage than Douglas fir (Pseudotsuga menziesii). Most of the
damage occurred within 15 feet of a trail centreline and originated within 3
feet of the groundline. Early summer logging may have resulted in more damaged
trees than might occur during other seasons. Future volume loss due to decay is
likely to be minimal because a low percentage of scars were considered
vulnerable to wood-decaying fungi.
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15. Binkley, D. 1984. Importance of
size-density relationships in mixed stands of Douglas-fir and red alder.
Forest-Ecology-and-Management 9(2): 81-85.
Keywords: thinning
growth
tree/stand health
Abstract: Pairs
of Douglas-fir, and Douglas-fir and red alder (Alnus rubra) stands were
examined at four locations (in Oregon, Washington and British Columbia) for patterns in average tree size as a function of stand
density. On fertile sites, the mixed stands experienced higher mortality than
the pure conifer stands. On infertile sites, the pure conifer stands were well
below the maximum tree size and density relationship compared to fertile sites
or mixed stands, suggesting under-utilized site resources were available for
nitrogen-fixing alder.
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16. Binkley, D. and P. Reid. 1984.
Long-term responses of stem growth and leaf area to thinning and fertilization
in a Douglas-fir plantation. Canadian-Journal-of-Forest-Research 14(5):
656-660.
Keywords: fertilization
thinning
tree morphology
carbon allocation
growth
Abstract: Replicated
thinning and nitrogen fertilization plots in a 53-year-old plantation in Washington State were examined for repsonses in stem growth, leaf area, and
stem growth per unit leaf area. Although measurements occurred 20-30 yr after
plot installation, substantial effects from the various treatments were still
present. Thinning reduced leaf area of the stands but increased stem growth per
unit leaf area, resulting in little difference in stem growth per ha over the
5-yr measurement period (1977-81). Fertilization increased both stand leaf area
and stem growth per unit leaf area, and more than doubled 5-yr stem growth per
ha. Consideration of the role of leaf area and stem growth per unit leaf area
in determining stand treatment responses may account for much of the variation
found among replicates of treatments or between studies on different sites.
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17. Bodner, J. 1984. Effect of thinning and fertilization on wood properties and
intra-ring characteristics in young Douglas-fir. Holzforschung-und-Holzverwertung
36(1): 5-11.
Keywords: fertilization
thinning
wood quality
Abstract: Studies
were made on samples from a total of 21 trees (felled in 1982) from 42-yr-old
control and thinned/[N] fertilizer-treated stands near
Sweet Home, Oregon, and a 48-yr-old thinned stand near Corvallis. Wood properties, studied between and within treatments,
included ring density (analysed by X-ray densitometry), earlywood and latewood
density, min. earlywood density, max. latewood
density, and ring width. There was n.s.d. in av. wood density between
treatments. There were significant between-treatment differences in MOE and MOR. Heavy thinning (during the juvenile wood formation phase)
reduced latewood fibre length by 26.5%. Min. earlywood
density and max. latewood density were the most
important components of ring density.
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18. Brandeis, T.J., M. Newton and
E.C. Cole. 2001. Underplanted conifer seedling survival and growth in thinned
Douglas-fir stands. Canadian-Journal-of-Forest-Research 31(2): 302-312.
Keywords: planting operations
thinning
commercial thinning
site preparation
chemical preparation
release treatments
chemical release
growth
tree/stand health
regeneration
Abstract: In a
multilevel study conducted at the Oregon State University's McDonald-Dunn
Research Forest, Oregon, USA, to determine limits to underplanted conifer
seedling growth, Douglas-fir (Pseudotsuga menziesii), grand fir (Abies
grandis), western redcedar (Thuja plicata) and western hemlock (Tsuga
heterophylla) seedlings were planted in January 1993 beneath second-growth
Douglas-fir stands that had been thinned in 1992 to basal areas ranging from 16
to 31 m2/ha. Understorey vegetation was treated with a broadcast herbicide
(glyphosate + imazapyr) application prior to thinning, a directed release
herbicide (glyphosate, plus triclopyr for tolerant woody stems) application 2
years later, or no treatment beyond harvest disturbance. Residual overstorey
density was negatively correlated with percent survival for all four species.
Broadcast herbicide application improved survival of grand fir and western
hemlock. Western redcedar, grand fir and western hemlock stem volumes were
inversely related to overstorey tree density and this effect increased over time.
There was a strong indication that this was also the case for Douglas-fir.
Reduction of competing understorey vegetation resulted in larger fourth-year
stem volumes in grand fir and western hemlock.
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19. Brandeis, T.J., M. Newton and
E.C. Cole. 2002. Biotic injuries on conifer seedlings planted in forest
understory environments. New Forests 24:1-14.
Keywords: planting operations
site preparation
chemical preparation
release treatments
chemical release
thinning
tree/stand protection
growth
tree/stand health
Abstract: The
effects of partial overstorey retention, understorey vegetation management, and
protective Vexar(R) tubing on the frequency and severity of biotic injuries in
a two-storied stand underplanted with western redcedar (Thuja plicata), Douglas-fir
(Pseudotsuga menziesii), grand fir (Abies grandis), and western hemlock (Tsuga
heterophylla) were investigated. The most prevalent source of damage was
browsing by black-tailed deer (Odocoileus hemionis columbiana); deer browsed
over 74% of Douglas-fir and over 36% of western redcedar seedlings one or more
times over the four years of this study. Neither the spatial pattern of
thinning (even or uneven) nor the density of residual overstorey affected
browsing frequency. Spraying subplots may have slightly increased browsing
frequency, but the resulting reduction of the adjacent understorey vegetation
increased the volume of all seedlings by 13%, whether or not they were browsed.
Vexar(R) tubing did not substantially affect seedling survival, browsing damage
frequency, or fourth-year volume. Greater levels of overstorey retention
reduced frequency of second flushing. Chafing by deer and girdling by rodents
and other small mammals began once seedlings surpassed 1 m in height.
Essentially all grand fir seedlings exhibited a foliar fungus infection.
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20. Brix, H. 1984.
Effects of thinning and nitrogen fertilization on growth of Douglas-fir:
relative contribution of foliage quantity and efficiency.
Canadian-Journal-of-Forest-Research 13(1): 167-175.
Keywords: fertilization
thinning
growth
carbon allocation
tree morphology
Abstract: [See FA
43, 1948, 3839] On Vancouver Island, aboveground biomass and annual production
over 7 yr was studied in relation to thinning and
nitrogen fertilization at 24 yr old. Biomass yield of both treatments increased
during the first 3-4 yr then decreased for fertilization but not with thinning.
Treatments doubled biomass production of individual trees over the study period
when applied separately and quadrupled it when combined. Annual biomass
production per unit of foliage (E) increased during the first 3-4 yr, but was
at or below control level after 7 yr. E accounted for 20, 37, and 27% of the stemwood
dry matter response to thinning, fertilization and the combined treatments,
respectively; the remainder was attributed to an increase in foliage biomass.
Thinning, but not fertilization, influenced distribution of radial growth along
the stem, increasing growth only below the top one-third of the stem. This
pattern was related to crown development.
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21. Brix, H. 1993. Fertilization and
thinning effect on a Douglas-fir ecosystem at Shawnigan Lake: a synthesis of project results. B.C.
Ministry of Forests FRDA-Report 196. X + 64 p.
Keywords: fertilization
thinning
growth
tree morphology
tree/stand health
carbon allocation
wood quality
tree physiology
photosynthesis
economics
Abstract:
Treatments were initiated in 1970-71 in a 24-year-old Douglas fir (Pseudotsuga
menziesii) near Shawnigan Lake, Vancouver Island, British Columbia, to
determine the effects of 3 intensities of thinning (removing none, one-third
and two-thirds of basal area) and 3 levels of urea fertilizer (0, 224 and 448
kg N/ha) on the growth and biology of the trees. Subsidiary experiments were
established during 1972-87 to examine the effects of high doses of urea
(672-1344 kg N/ha), ammonium nitrate as an N source instead of urea,
understorey response to thinning and fertilizer, and responses to P and S
fertilizer.
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22. Brix, H. and A.K. Mitchell. 1983.
Thinning and nitrogen fertilization effects on sapwood development and
relationships of foliage quantity to sapwood area and basal area in
Douglas-fir. Canadian-Journal-of-Forest-Research 13(3): 384-389.
Keywords: fertilization
thinning
tree morphology
tree physiology
Abstract: A
24-yr-old stand in British Columbia was treated in 1971-72 with various intensities and
combinations of N fertilization and thinning. For 5-9 yr after treatments,
trees were sampled to determine effects on foliage quantity and sapwood
characteristics at varying stem ht. together with their relationships. Sapwood
width remained relatively constant up the stem where heartwood was present, but
the number of annual rings it contained decreased with ht. The sapwood width at
b.h. increased with stem diam.; treatments had little effect on % sapwood at
b.h. The ratio of foliage mass to sapwood cross-sectional area changed for
different portions of the crown and was lower when based on sapwood area at
b.h. than at base of live crown. Significant linear relationships of foliage
mass and area to sapwood area at b.h. were found, but relationships of foliage
to b.a. were just as close for all treatments;
treatments significantly affected these relationships with control trees having
the lowest regression slopes.
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23. Brix, H. and A.K. Mitchell. 1986.
Thinning and nitrogen fertilization effects on soil and tree water stress in a
Douglas-fir stand. Canadian-Journal-of-Forest-Research 16(6): 1334-1338.
Keywords: thinning
fertilization
soil properties
tree physiology
Abstract: Soil
and tree water potentials were studied for 10 yr in a Douglas fir stand near
Shawnigan Lake, British Columbia that was treated when 24 yr old with heavy
thinning (removing superscript 2/3 of b.a.) and/or fertilization with 448 kg
N/ha as urea. Control plots were not thinned or fertilized. Throughout the 10
yr, thinning increased soil water potential during the dry summer periods
(July-early Oct.) by as much as 1 MPa. The effect of fertilization on soil water
potential was slight and nonsignificant, and only apparent towards the end of
the study in spite of large increases in leaf area (50% after 7 yr).
Fertilization increased water use efficiency. The favourable soil water
conditions produced by thinning led to improved shoot water potential only
during predawn and early morning. Removal of understorey in a thinned and
fertilized plot did not affect soil or shoot water potential.
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24. Buermeyer, K.R. and C.A. Harrington. 2002. Fate of overstory trees and patterns of regeneration
12 years after clearcutting with reserve trees in Southwest Washington. Western-Journal-of-Applied-Forestry 17(2): 78-85.
Keywords: thinning
regeneration
tree/stand health
Abstract: Changes
in management objectives for some forestlands in the Pacific Northwest have spurred interest in the creation of multistoried
stands and the use of natural regeneration systems, but data on such systems
are lacking. We assessed the status of the overstory trees and the regeneration
12 yr after a clearcut harvest with reserve trees in an even-aged, 145-yr-old
Douglas-fir stand on a moderately productive site (site class 3) in southwest Washington. The 15 ha harvest unit was superimposed over two areas
differentially thinned 15 and 34 yr before clearcutting. The clearcut harvest
retained 18 trees/ha with a mean diameter of 63 cm. The reserved overstory
trees had a 93% survival rate after 12 yr; most dead trees had been windthrown.
Diameter growth for the reserved trees averaged 3.3 cm and was greatest during the
most recent 3 yr period, which also had the highest growing-season
precipitation. In a 1 ha mapped area, there were 5,854 seedlings/ha, and more
than 99% of the regeneration was Douglas-fir. Most seedlings were less than 2 m
tall. Seedling density was somewhat clumped (value of 2.1 for Pielou's index of
nonrandomness), but 79% of randomly located 4.04 m2 (mil-acre) plots and 98% of
5x5 m grid cells had at least one conifer seedling. There was no obvious
pattern of regeneration based on direction from the reserved trees, but both
seedling density and seedling size within the drip lines of reserved tree
crowns were less than in the rest of the area. The number of seedlings was
similar on the two halves of the plot corresponding to the original thinning blocks,
but seedling size and age differed. In the half of the study plot that had been
twice lightly thinned, only 14% of the seedlings were >0.5 m tall; however,
41% of the seedlings were >0.5 m in the block that had been thinned more
heavily. There was no difference between the thinning blocks in the ages of
seedlings <less or =>0.5 m tall (mean age of 5 yr). This example of
clearcutting with reserve trees resulted in reasonable survival of the
overstory trees and adequate stocking but slow growth rates in the naturally
regenerated Douglas-fir. Heavier thinning before harvest was associated with
more advance regeneration, more shrub cover, and less windthrow of the reserved
trees than in the more lightly thinned block. If an abundance of tree species
other than Douglas-fir was desired on this site, interplanting would be
required.
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25. Busing, R.T. and S.L. Garman.
2002. Promoting old-growth characteristics and long-term wood production in
Douglas-fir forests. Forest-Ecology-and-Management 160(1/3): 161-175.
Keywords: thinning
yield
wood quality
Abstract: Trade-offs
among wood production, wood quality and ecological characteristics in the
management of harvested forest stands are explored through model simulation of
various silvicultural regimes. Long-term production of merchantable wood,
production of various types of high-quality wood, and the level of certain
quantitative ecological indicators are projected for coniferous forests of
Pacific Northwestern USA. The set of ecological indicators used is based on the
species composition and physical structure of old, unlogged forest stands.
Simulations are performed with an ecological model of forest stand dynamics
that tracks the fate of live and dead trees. Short rotations (<50 years)
produce the least amount of high-quality wood over the multi-century simulation
period. They also fail to generate ecological attributes resembling those of
old forest stands. Production of high-quality wood is moderate to high under
all rotations of 80 years or more; however, most ecological indicators require
longer rotations unless alternatives to clear felling are applied. Alternatives
examined include retention of 15% cover of live tree canopy at each harvest in
combination with artificial thinning between harvests. Thinning from below can
expedite the development of large live and dead trees, and canopy height
diversity without greatly diminishing wood quantity or quality. Proportional
thinning retains understorey stems, thereby expediting the recruitment of
shade-tolerant trees. A possible drawback to thinning, particularly
proportional thinning, is the diminished production of
clean-bole wood at rotations of 150 and 260 years. It is concluded that most
wood quantity, wood quality and ecological objectives can be met with long
rotations (approximately 260 years). Certain objectives can be met with shorter
rotations (80-150 years) when treatments of thinning and canopy tree retention
are applied.
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26. Carter, R. and R. Scagel. 1989.
The effects of stand density and fertilization on stand development in immature
coastal Douglas-fir. B.C. Ministry of Forests FRDA-Report
094. i + 15 p.
Keywords: fertilization
thinning
growth
tree morphology
Abstract: The
effects of urea fertilizer were studied in Pseudotsuga menziesii stands spaced
to 500, 750 and 1000 stems/ha in coastal British Columbia.
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27. Chen, J.M. and T.A. Black. 1992.
Foliage area and architecture of plant canopies from sunfleck size
distributions. Agricultural-and-Forest-Meteorology 60(3/4): 249-266.
Keywords: thinning
pruning
tree morphology
Abstract: A
Poisson model is developed to describe sunfleck or gap size distributions
beneath clumped plant canopies. This model is based on the assumption that
foliage clumps are randomly distributed in space and foliage elements are
randomly distributed within each clump. Using this model, the foliage clumping
index, leaf area index (L), clump area index, element area index in each clump,
and element and clump widths were successfully derived for two artificial
canopies and a thinned and pruned Douglas-fir (Pseudotsuga menziesii) forest
stand. It is shown that existing theories for deriving L from measurements of
canopy gap fraction have limitations, and use of canopy architectural
information derived from canopy gap size distribution can substantially improve
the technique for indirectly measuring L of plant canopies.
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28. Christiansen, E.C. and S.G.
Pickford. 1991. Natural abatement of fire hazard in Douglas-fir blowdown and
thinning fuelbeds. Northwest-Science 65(4): 141-148.
Keywords: thinning
precommercial thinning
tree/stand health
Abstract: The
changes over time in fuelbed loading and depth in precommercially thinned and
windthrown low altitude stands of Douglas fir (Pseudotsuga menziesii) were
investigated in the Bull Run Watershed, Oregon, using standard fuel inventory techniques. Non-linear
least squares regressions were fitted to the resulting data. Slash from
precommercial thinning lost half of its original loading and depth within 2 yr.
No foliage was retained on twigs and branches after 1 yr. Changes in fuels from
windthrown trees were similar to those in slash, except that more material was
present initially. Fine fuels (<3 inches in diameter) decreased to
background levels within 2-4 yr, but large fuels persisted for longer. Sound
logs became rotten after about 80 yr. The study confirmed that the fire hazard
after precommercial thinning slash and wind throw was abated after 3 yr.
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29. Cole, D.W., M.L. Rinehart, D.G.
Briggs, C.L. Henry and F. Mecifi. 1984. Response of Douglas fir to sludge
application: volume growth and specific gravity. In Proceedings of the
Technical Association of the Pulp and Paper Industry 1984 Research and
Development Conference, Appleton, Wisconsin, September 30-October 3. pp. 77-84.
Keywords: fertilization
thinning
growth
wood quality
Abstract: In 1977
and 1980 municipal sludge was applied to a 60-yr-old lowland Douglas fir stand
in Washington State. Application procedures and rates and suitable sites for
treatment are described. There was a 6 yr av. diam. growth response of 93% in
unthinned and 48% in thinned stands treated with 142 t/ha sludge and a vol.
growth response of 53 and 42%, respectively. The accelerated rate of growth has
not shown signs of decreasing since treatment. Relative density of sludge-grown
wood was 10-15% less than that of untreated wood, but within the range for
Douglas fir grown on higher land. This is thought to be a result of the change
in forest site produced by the sludge treatment.
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30. Collier, R.L. and E.C. Turnblom.
2001. Epicormic branching on pruned coastal Douglas-fir.
Western-Journal-of-Applied-Forestry 16(2): 80-86.
Keywords: pruning
thinning
wood quality
tree morphology
Abstract: The
Stand Management Cooperative (SMC 1998) at the University of Washington, USA,
conducted live crown reduction experiments in the Pacific Northwest regions of
the USA, to better understand the dynamics of the response of coastal Douglas
fir (Pseudotsuga menziesii) to pruning. A detailed report on how frequently
epicormic branches occur, where they occur on the bole, whether or not their
occurrence is related to stand density or the amount of crown removed, and how
epicormic sprouting may affect log grade, is presented. The experiments include
fifty-six 0.08 ha pruning plot in 18 installations in British Columbia, Oregon and Washington. As part of the monitoring process, a subset of 38 plots
in 12 installations was examined for the occurrence and size of epicormic
branches 4 years after the initial pruning treatments. Results showed that
epicormic branching was most severe on the south and west sides of trees. When
epicormic branching was severe, sprouts occurred both at nodes (or whorls) and
along internodes. Less severe or moderate sprouting tended to originate mainly
in nodes. The risk of epicormic branching is minimal as long as the pruning
treatment does not reduce the live crown by more than 40% and the stand has 500
or more stems/ha. The highest risk of epicormic branching was found to be when
the live crown is reduced by more than 40%, and the stand carries less than 500
stems/ha.
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31. Cruickshank, M.G., D.J. Morrison
and Z.K. Punja. 1997. Incidence of Armillaria species in precommercial thinning
stumps and spread of Armillaria ostoyae to adjacent Douglas-fir trees.
Canadian-Journal-of-Forest-Research 27(4): 481-490.
Keywords: thinning
precommercial thinning
tree/stand health
Abstract: The
frequency of Armillaria species in precommercial thinning stumps and the
interaction at root contacts between Douglas fir (Pseudotsuga menziesii) crop
trees and stumps colonized by A. ostoyae were investigated at sites in four
biogeoclimatic zones along a transect from the coast through the southern
interior of British Columbia. The frequency of stumps colonized by A. ostoyae
and A. sinapina varied among lower, mid, and upper slope transects. On coastal
sites, A. sinapina dominated fresh hygrotopes and A. ostoyae dominated slightly
dry hygrotopes, and the frequency of both fungi was low on moist hygrotopes. On
interior sites, A. ostoyae was found over all hygrotopes, but with lower
frequency on the driest sites. The distribution of the two Armillaria species
on sites is apparently determined by anoxia associated with periodic soil
saturation, by drying of the soil, and by host response limiting spread of
pathogenic species. At root contacts between colonized stump roots and crop
tree roots, transfer and infection by A. ostoyae occurred more frequently in
moist biogeoclimatic zones than dry ones. Lesion size on crop tree roots was
related to inoculum volume at some sites and to stump root diameter at others. The percentage of lesions on roots at which crop trees formed
callus was associated with tree bole volume. The results indicate that
there will be crop tree mortality following precommercial thinning, especially
where inoculum levels are high in the Interior Cedar-Hemlock and Interior
Douglas fir biogeoclimatic zones.
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32. Curtis, R.O. 1987.
Levels-of-growing-stock cooperative study in Douglas-fir: Report No. 9 - some
comparisons of DFSIM estimates with growth in the levels-of-growing stock
study. Pacific-Northwest-Research-Station,-USDA-Forest-Service Research-Paper PNW-RP-376. 34 p.
Keywords: thinning
commercial thinning
growth
tree/stand
health
computer modeling
Abstract: Initial
stand statistics for the 9 levels-of-growing-stock (LOGS) study installations
in Oregon and Washington, USA, and Vancouver Island, British
Columbia, Canada, were projected by the Douglas fir (Pseudotsuga menziesii)
stand simulation program (DFSIM) over the available periods of observation.
Thinnings were simulated by use of observed top height trends, actual residual
basal areas, and actual ratios of cut tree diameters to stand diameter before
cutting (d/D). Estimates were compared with observed gross and net volumes and
basal area growth, net change in quadratic mean diameter, and change in number
of trees. Although the LOGS installations included regimes quite different from
those in most of the data used to construct DFSIM, overall agreement was
reasonably good. Results indicated some density-related bias in the thinned
stands and a need for revision in the method used to control the maximum
density in the DFSIM program and in the associated mortality estimates.
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33. Curtis, R.O., G.W. Clendenen and
D.J. DeMars. 1981. A new stand simulator for coast Douglas-fir: DFSIM user's
guide. Pacific-Northwest-Forest-and-Range-Experiment-Station,-USDA-Forest-Service General-Technical-Report
PNW-GTR-128. ii
+ 79 p.
Keywords: planting operations
thinning
precommercial thinning
commercial thinning
fertilization
yield
computer modeling
Abstract: A
description of a computer program, written in FORTRAN IV, for simulating
managed stands. The program has been developed from remeasured plot data
contributed by many organizations in the Pacific Northwest USA. It can produce
yield tables which include estimates of effects of initial spacing,
precommercial and commercial thinning and addition of N fertilizer. Topics
discussed include program limitation and potential for further development.
Appendices include operating instructions and notes on testing. The program is
available from the authors on request.
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34. Curtis, R.O. and
D.D. Marshall. 1986. Levels-of-growing-stock cooperative study in Douglas-fir.
Report no. 8 - The LOGS study: twenty-year results. Pacific Northwest Research Station, USDA Forest Service Research-Paper PNW-RP-356. v + 113 p.
Keywords: thinning
commercial thinning
growth
Abstract: A
further report in a series on 9 study areas in Oregon, Washington and British Columbia. The programme aimed to determine relations between
growing stock and vol., b.a. and diam. growth for 8
thinning regimes. Results presented are mainly from 5 site class II
installations. Growth was strongly related to growing stock. Thinning
treatments produced marked differences in volume distribution by tree sizes.
There were considerable unexplained differences in productivity between
installations, beyond those attributable to site quality. During the 4th
treatment period (32-42 yr old in site class II sites) c.a.i. was approx. twice
m.a.i. An evaluation is given of the LOGS study design.
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35. Curtis, R.O. and D.D. Marshall.
2002. Levels-of-growing-stock cooperative study in Douglas-fir: report no. 14 -
Stampede Creek: 30-year results. Pacific-Northwest-Research-Station,-USDA-Forest-Service Research-Paper PNW-RP-543. xi + 77 p.
Keywords: thinning
commercial thinning
growth
yield
tree morphology
tree/stand health
Abstract: Results
of the Stampede Creek installation of the levels-of-growing-stock (LOGS) study
in Douglas-fir (Pseudotsuga menziesii) are summarized. To age 63 (planned
completion of 60 feet of height growth), volume growth
on the site III natural stand has been strongly related to level of growing
stock, but basal area growth-growing stock relations were considerably weaker.
Marked differences in tree size distributions have resulted from thinning.
Periodic annual volume increments at age 63 are two to three times greater than
mean annual increment; this stand is still far from culmination. Results for
this southwest Oregon installation are generally similar to those reported from
other LOGS installations, although development has been slower than on the site
II installations that make up the majority of the series.
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36. Curtis, R.O., D.D. Marshall and
J.F. Bell. 1997. LOGS: a pioneering example of silvicultural research in coast
Douglas-fir. Journal-of-Forestry 95(7): 19-25.
Keywords: thinning
commercial thinning
growth
yield
Abstract: A
regional levels-of-growing-stock (LOGS) study of young Douglas fir (Pseudotsuga
menziesii) stands in western Oregon and western Washington, USA and Vancouver Island, British
Columbia, Canada, was conducted between 1961 and 1970. The objective was to
determine how the amount of growing stock retained in repeatedly thinned stands
of P. menziesii affects cumulative wood production, tree size and growth:growing stock ratios. Nine LOGS installations were
established during the study period, each consisting of 27 one-fifth acre
plots, with 8 thinning treatments (and controls). All plots received initial
calibration thinning. After the first 10 feet of height growth and at intervals
of 10 feet thereafter, 5 subsequent thinning treatments were made. As of 1994,
all installations on site class II, and most installations on site classes III
and IV had completed the planned thinning sequence over 60 ft of height growth.
Periodic annual increment of both basal area and volume was clearly related to
basal area of growing stock and several measures of density. Thinning
accelerated diameter growth, and diameter and volume distributions differed
greatly among treatments. Mean annual increment and periodic annual increment
showed no sign of approach to culmination in either total or merchantable cubic
volume. Cumulative volume production (live stand plus thinning) of the controls
exceeded all thinning treatments to date when measured in total cubic volume of
all trees, although when volume was measured in merchantable cubic feet several
thinning treatments exceeded net volume production of the controls. A
discussion of the results includes: a comparison with other thinning studies;
an analysis of application of the Langsaeter hypothesis (that the same cubic
volume production could be obtained over a wide range of stand densities);
growth trends and rotations; thinning gains; non-timber values; and critical
analysis of the study design. The continuing value of the demonstration stands
is discussed.
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37. Curtis, R.O., D.D. Marshall and
D.S. DeBell. 2004. Silvicultural options for young-growth Douglas-fir forests:
the Capitol Forest study - establishment and first results. Pacific Northwest-Research-Station,-USDA-Forest-Service General-Technical-Report
PNW-GTR-598. xi
+ 110 p.
Keywords: thinning
commercial thinning
economics
soil properties
Abstract: This
report describes the origin, design, establishment and measurement procedures
and first results of a large long term cooperative study comparing a number of
widely different silvicultural regimes applied to young-growth Douglas-fir
(Pseudotsuga menziesii) stands managed for multiple objectives. Regimes consist
of (1) conventional clear felling followed by intermediate thinning; (2)
retention of reserve trees to create a two-aged stand; (3) small patch cuts
dispersed within a thinned matrix, repeated at approximately 15-year intervals
to create a mosaic of age classes; (4) group selection within a thinned matrix
on an approximate 15-year cycle; (5) continued thinning on an extended
rotation; and (6) an untreated control. Each of these regimes is on
operation-size units (approximately 30 to 70 acres each). A LIDAR system was
used to scan the surface of the 2 miles2 that encompass the Blue Ridge study site on the Capitol State Forest, near Olympia, Washington, USA. This measurement technology emits laser pulses that are
reflected by vegetation, buildings, or the ground surface. Output variables
from the study to be evaluated include conventional timber growth and yield
statistics, harvest costs, sale layout and administration costs, aesthetic
effects and public acceptance, soil disturbance, bird populations, and economic
aspects. Descriptive statistics and some initial results are presented for the
first replicate, established in 1997-98.
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38. Dangerfield, J. and H. Brix.
1981. Comparative effects of ammonium nitrate and urea fertilizers on tree
growth and soil processes. In Proceedings: Forest
Fertilization Conference, University of Washington, Seattle, Washington, USA. Eds. S.P. Gessel, R.M. Kenady
and W.A. Atkinson. pp. 133-139.
Keywords: fertilization
thinning
growth
tree physiology
Abstract: Growth
response of Douglas-fir to ammonium nitrate and urea, applied at rates of 200
and 400 pounds per acre (224 and 448 kilograms of nitrogen per hectare), was
studied over a 7-year period at Shawnigan Lake, B.C. Diameter growth was 21 and
9 percent better, respectively, for the two rates with ammonium nitrate than
with urea in unthinned plots and 7 percent better for plots that had been
thinned and received 400 pounds per acre (448 kilograms nitrogen per hectare).
Foliar nitrogen concentrations also increased most with ammonium nitrate
fertilzization during the first 2 years, indicating that nitrogen from this
source was initially more readily available to the trees. This is explained in
part by the greater mobility of nitrate supplied by ammonium nitrate and by
nitrogen immobilization in buildup of bacterial populations with urea.
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39. DeBell, D.S., C.A. Harrington and J. Shumway. 2002. Thinning shock and response to fertilizer less than
expected in young Douglas-fir stand at Wind River Experimental Forest. Pacific-Northwest-Research-Station,-USDA-Forest-Service Research-Paper PNW-RP-547. ii + 20 p.
Keywords: fertilization
thinning
precommercial thinning
growth
Abstract: Three
thinning treatments (thinned to 3.7 by 3.7 m, thinned to 4.3 by 4.3 m, and an
unthinned control treatment with nominal spacing averaging 2.6 by 2.6 m) were
installed in a 10-year-old Douglas-fir (Pseudotsuga menziesii) plantation
growing on a low-quality site at the Wind River Experimental Forest in southwest Washington, USA. Two years after thinning, two fertilizer treatments were
superimposed on the design (0 and 224 kg per ha of nitrogen applied as ammonium
nitrate). Diameter growth increased with increasing spacing throughout the
6-year study period, and it was also increased by fertilizer in both the
thinned and unthinned (control) treatments. Thinning shock, a reduction in
height growth after thinning, was expected at this study site because severe
thinning shock had been documented in earlier nearby trials. Height growth was
initially reduced slightly by thinning, but by the third 2-year period after
thinning, height growth in thinned, unfertilized treatments was equal to or
greater than height growth in the unthinned, unfertilized treatment. Fertilizer
application increased height growth on average by 13 per cent in the first 2
years after fertilizer application. In the third and fourth years after
fertilizer application, however, fertilizer increased average height growth by
9 per cent, but the increase was substantial (16 per cent) only in the
unthinned control treatment. The mild, ephemeral nature of thinning shock in
our study was in contrast to the severe, long-lasting shock in earlier studies
at Wind River. The milder shock in our study could be related to one or
more of the following: (1) thinning was done at an early age, (2) impacts of
fire (natural or prescribed) preceding planting were minor, and (3) seed source
of the planted stock was appropriate for the location. Based on comparisons
with other studies at Wind
River and elsewhere, we suspect
that use of nonlocal, maladapted seed sources in the earlier studies may have
predisposed those trees to thinning shock. Furthermore, we suspect that the
much higher responses to fertilizer application reported in the earlier studies
may be associated with intense natural fires prior to planting, and the reduced
nutritional status of those sites may have been further exacerbated by the use
of maladapted seed sources.
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40. Drever, C.R. and K.P. Lertzman.
2003. Effects of a wide gradient of retained tree structure on understory light
in coastal Douglas-fir forests. Canadian-Journal-of-Forest-Research 33(1):
137-146.
Keywords: thinning
stand conditions
Abstract: We
characterize understorey light of seven stands that varied along a gradient of
tree retention. Using hemispherical canopy photographs and digital image, we
estimated gap light or solar radiation reaching the understorey through the
canopy. Using nonlinear regressions, we related gap light to several structural
attributes in the examined silvicultural treatments. The silvicultural
treatments affected both the median and range of gap light in the understorey.
As overstorey removal increased from uncut second growth to green-tree
retention, the median value of light increased from 8 to 68% full sun, while
the range of light increased from 3-22% to 26-88% full sun. We found strong,
significant, and negative nonlinear relationships between gap light at a
particular microsite (0.04 ha) in the understorey and the height, diameter at
breast height, density, and volume of surrounding retained trees
(ra2=0.77-0.94). These relationships can aid planning of treatments that retain
forest structure, such as variable retention, by allowing predictions of
understorey light from commonly used field data. These predictions allow forest
managers to understand some of the ecological consequences and tradeoffs
associated with retaining structure during harvesting.
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41. Duke, K.M., G.M. Townsend and
W.A. White. 1989. An economic analysis of fertilization and thinning effects on
Douglas-fir stands at Shawnigan Lake. Canadian-Forest-Service, Pacific and Yukon Region Information-Report BC-X-312. v + 19 p.
Keywords: fertilization
thinning
economics
computer modeling
Abstract: A
single-tree density-dependent growth model was used to project, from age 24 to
age 120 yr, 9 combinations of thinning and fertilizer application (nitrogen as
urea or ammonium nitrate) in Douglas fir (Pseudotsuga menziesii) near Shawnigan
Lake, British Columbia. Costs and benefits were estimated as a function of
stand diameter, and forestry investment criteria were used to evaluate each
treatment on both an incremental and a regime basis. The effect of rising real prices, and the treatment of silvicultural costs as an
initial investment or as a harvest cost were also studied.
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42. Edmonds, R.L. and T. Hsiang. 1987. Forest floor and soil influence on response of Douglas-fir to
urea. Soil-Science-Society-of-America-Journal 51(5): 1332-1337.
Keywords: fertilization
thinning
growth
soil properties
Abstract: Data
from the Regional Forest Nutrition Research Project (RFNRP) in Washington and Oregon were analyzed to improve stand-specific prediction of
Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] response
to urea fertilization. The response variable (relative difference in
volume growth between fertilized and control plots 4 yr after fertilization
with 448 kg N/ha) was regressed against 28 stand and site variables (e.g., age,
elevation, forest floor C/N ratio, soil cation exchange capacity, etc.) using
stepwise multiple regression analysis. Data from 120 installations were
stratified by thinning level (thinned or unthinned), geographic location
(provinces), and site quality (site index and class). Forest floor
C/N ratio was the dominant variable related to response. In thinned
installations of high site quality (site classes 1 and 2), 60% of variation in
response was explained by the forest floor C/N, and 75% of the variation in
response was explained with inclusion of surface soil exchangeable K. In
thinned, low site quality stands, response was not as well related to forest
floor C/N. Analysis of the data by province indicated that S may be limiting in
southwest Oregon and P in coastal Washington.
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43. El Kassaby, Y.A. and A.
Benowicz. 2000. Effects
of commercial thinning on genetic, plant species and structural diversity in
second growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands.
Forest-Genetics 7(3): 193-203.
Keywords: thinning
commercial thinning
genetic relationships
Abstract: The
impact of commercial thinning on biodiversity was studied in two Douglas-fir
(Pseudotsuga menziesii) plantations, Weeks Lake (WL) and Fairservice Creek (FC)
located on southern Vancouver Island, British
Columbia, Canada. The age of the stands at thinning was 53 and 70 years for
FC and WL, respectively. Other tree species were also present in both sites due
to natural regeneration. Biodiversity was evaluated before and after commercial
thinning with respect to tree species composition/abundance, tree species
genetic diversity assessed by allozyme analysis and stand structural diversity
represented by the diameter class (5-cm) distribution. In addition, understorey
plant species diversity was monitored in WL and FC for 4 and 5 years following
thinning, respectively. Tree species composition changed in both plantations in
a similar fashion as the proportion of Douglas-fir increased at the expense of
all other tree species. Stand structural diversity was simplified due to the
decreased number of trees in small diameter classes. These results were
expected since the commercial thinning was conducted to promote the growth of
Douglas-fir. Genetic diversity parameters (average number of alleles per locus,
percent polymorphic loci and expected heterozygosities) did not differ
significantly before and after thinning; however, thinning resulted in a loss
of 8 and 7 alleles across species for FC and WL, respectively. Most of the
allelic loss occurred in the naturally regenerated species (93%). This allelic
loss represents 7 and 6% of the total alleles present in FC and WL,
respectively. Thus, only one allele was lost from the crop tree in the FC
plantation. Understorey vegetation species richness decreased the year
following commercial thinning and then consistently increased over time in both
plantations. A total of 17 and 9 new species colonized FC and WL, respectively.
One species was replaced in each plantation. In FC, diversity of the
understorey plant community based on the Shannon
diversity index (H) changed in an increasing linear trend that corresponded to
the increase in species richness. On the other hand, H in WL remained stable.
Species evenness (H/Hmax) did not change in WL and FC over the course of study
except for seasonal fluctuations. Rare species diversity increased over time in
both plantations.
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44. Emmingham, W.L., P. Oester, M.
Bennett, F. Kukulka, K. Conrad and A. Michel. 2002. Comparing short-term
financial aspects of four management options in Oregon: implications for uneven-aged management. Forestry-Oxford
75(4): 489-494.
Keywords: thinning
commercial thinning
economics
yield
Abstract: Private
family forest owners are often more interested in comparing short-term
financial outcomes of management options, as opposed to longer time horizons
and classical economic analyses including net present value. Therefore, we compared
projected 10-year value of timber and land for four theoretical management
scenarios starting with stands ripe for thinning. The options were (1) hold for
10 years (i.e. no thinning), (2) thin for even-age, or (3) partial cut for
uneven-age and (4) clearcut now. To simulate the outcomes of these scenarios,
we marked and measured 2-ha plots in 10 stands typical
of private forest ownerships across Oregon and projected timber yields and revenues. The financial
analysis included current market values for logs, payment of taxes and typical
reforestation costs and computation of net asset values (NAV) at a 7 per cent
interest rate. The hold option consistently gave the highest NAV for timber and
land after 10 years, and the thin option was within 2 per cent. For the eight
western Oregon stands, the partial-cut option averaged about 3 per cent
less, and the clearcut option ranged from 8 to 17 per cent less than holding.
Pine stands of eastern Oregon showed similar trends; however, all options were within about
6 per cent of the hold option. Thus, using financial criteria typical of those
used by private forest owners, we found that there was
little short-term financial loss in choosing to thin toward even-age, partial
cut toward uneven-age, or the hold approach in well-stocked stands.
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45. Entry, J.A., K. Cromack, Jr.,
R.G. Kelsey and N.E. Martin. 1991. Response of Douglas-fir to infection by
Armillaria ostoyae after thinning or thinning plus fertilization.
Phytopathology 81(6): 682-689.
Keywords: thinning
fertilization
tree/stand protection
growth
tree
morphology
carbon allocation
tree/stand health
tree physiology
Abstract: Second-growth
stands of Douglas-fir (Pseudotsuga menziesii) were thinned to a 5- x 5-m
spacing (TT); additional plots were thinned and fertilized once with 360 kg of
N (as urea)/ha (TF). An unthinned, unfertilized stand (UT) served as a control.
Ten years after treatment, trees were inoculated with 2 isolates of A. ostoyae.
Trees receiving the TF and TT treatments produced greater diameter growth, leaf
area, and wood production/msuperscript 2 leaf area per year than did those
under the UT treatment. Rates of infection by A. ostoyae were highest in trees
that received the TF and lowest in trees that received the TT treatment. Concn
of sugar, starch and cellulose in root bark tissue were highest in trees
receiving the TF treatment and lowest in trees receiving TT treatment. Concn of
lignin, phenolics and protein-precipitable tannins were highest in root bark
from TT trees and lowest in root bark from TF trees. Biochemical parameters of
root bark tissue were regressed with incidence of infection; coefficients of
determination (rsuperscript 2) ranged from 0.07 (starch) to 0.57 (phenolic
compounds). Ratios of the energetic costs of phenolic and of lignin degradation
to the energy available from sugars (Epd:Eas and
Eld:Eas) were correlated with incidence of infection (rsuperscript 2 = 0.77 and
0.70, respectively). It is concluded that thinning combined with fertilization
may predispose P. menziesii trees to infection by A. ostoyae by lowering concn
of defensive compounds in root bark and increasing the energy available to the
fungus to degrade them.
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46. Feller, M.C., J.P. Kimmins and
K.A. Scoullar. 1983. FORCYTE-10: calibration data and simulation of potential
long-term effects of intensive forest management on site productivity, economic
performance, and energy benefit/cost ratio. In I.U.F.R.B.
Symposium on. Forest Site and Continuous Productivity; Seattle, Washington; August 22-28, 1982. Eds. R. Ballard and S.P.
Gessel. Pacific-Northwest-Forest-and-Range-Experiment-Station,
USDA-Forest-Service General-Technical-Report PNW-GTR-163 Part B. 179-200 pp.
Keywords: thinning
fertilization
soil properties
economics
computer modeling
Abstract: FORCYTE
(FORest nutrient Cycling and Yield Trend Evaluator) is a computer
simulation model of forest plant biomass production, litterfall, and
decomposition, complete with nutrient cycling, nutrient limitation on growth,
and a variety of management interventions. The model is a computerized approach
to the estimation of the effects of varying thinning and fertilizer regimes,
utilization level, and rotation length on site nutrient budgets, stand
productivity, and the economic performance and energy efficiency of management.
The model has evolved over 5 years to its present version FORCYTE-10, which is
briefly described. Accompanying the development of FORCYTE, there has been a
series of field research projects. Detailed biomass and biogeochemical
descriptions of age sequences of Douglas-fir stands on both good and poor sites
have been prepared for purposes of model calibration and testing. The present
report summarizes some of the results of the FORCYTE-10 field studies on Vancouver Island, British
Columbia, and
presents some examples of the use of the model when calibrated with these data.
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47. Fight, R.D., J.M. Cahill, T.D.
Fahey and T.A. Snellgrove. 1988. A new look at pruning coast Douglas-fir.
Western-Journal-of-Applied-Forestry 3(2): 46-48.
Keywords: pruning
thinning
fertilization
economics
Abstract: A short
account of an evaluation of the financial returns of pruning coast Douglas fir
(Pseudotsuga menziesii), using new product-recovery information and computer software,
and assuming that: the analysis is for lumber, interest rates are 4 and 8%,
stands are fertilized 2 or 3 times and thinned periodically, and that trees
were pruned at age 20 yr. Results showed that higher returns from pruning could
be achieved by concentrating pruning in younger stands that have a higher site
index and that will be fertilized.
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48. Filip, G.M. and L.M. Ganio. 2004.
Early thinning in mixed-species plantations of Douglas-fir, hemlock, and true
fir affected by Armillaria root disease in Westcentral Oregon and Washington: 20 year results. Western-Journal-of-Applied-Forestry
19(1): 25-33.
Keywords: thinning
precommercial thinning
tree/stand protection
growth
tree/stand health
Abstract: Four
10- to 20-year-old plantations were treated to determine the effects of
precommercial thinning on tree growth and mortality caused by Armillaria root
disease in the Cascade
Range of western Oregon and Washington, USA. One plantation was Douglas-fir (Pseudotsuga menziesii)
and noble fir (Abies procera), one Douglas-fir and western hemlock (Tsuga
heterophylla), one Douglas-fir alone, and one Shasta red fir (Abies magnifica
var. shastensis) and mountain hemlock (Tsuga mertensiana). After 20 years,
differences in crop tree mortality between thinned and unthinned plots were not
significant (P=0.9768). Quadratic mean diameter growth of crop trees, however,
was significantly (P=0.0053) greater in thinned than in unthinned plots. Crop
tree basal area/ac growth was significantly (P=0.0008) greater in thinned
plots. There were no significant (P=0.6647) differences in basal area/ac growth
of all trees between thinned and unthinned plots. Apparently, from a
root-disease perspective, precommercial thinning does not affect incidence of
crop-tree mortality after 20 years, but individual and per acre tree growth of
crop trees increase significantly.
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49. Filip, G.M. and D.J. Goheen.
1995. Precommercial thinning in Pseudotsuga, Tsuga, and Abies stands affected
by armillaria root disease: 10-year results. Canadian-Journal-of-Forest-Research
25(5): 817-823.
Keywords: thinning
precommercial thinning
tree/stand protection
growth
tree/stand health
Abstract: Four
10- to 20-year-old stands were pre-commercially thinned to determine the
effects of thinning on tree growth and mortality caused by armillaria root
disease (Armillaria ostoyae) in the Cascade Range of western Oregon and
Washington, USA: one stand of Douglas fir (Pseudotsuga menziesii var.
menziesii) and noble fir (Abies procera), one of Douglas fir and western
hemlock (Tsuga heterophylla), one of Douglas fir alone, and one of Shasta red
fir (Abies magnifica var. shastensis) and mountain hemlock (Tsuga mertensiana).
After 10 years, differences in crop-tree mortality between thinned and
unthinned plots were not significant in any of the four stands. Tree radial
growth was significantly increased by thinning in 6 of 15 plots. Crop-tree
basal area (per hectare) growth was significantly greater in thinned plots.
Basal area (per hectare) growth of all trees was significantly greater in
unthinned plots. Apparently, from a root-disease perspective, pre-commercial
thinning does not affect the incidence of crop-tree mortality after 10 years,
but tree growth increases significantly.
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50. Gardner, E.R. 1990. Fertilization and thinning effects on a
Douglas-fir ecosystem at Shawnigan Lake: 15-year growth response. Canadian-Forest-Service,
Pacific and Yukon Region Information-Report BC-X-319. ix + 42 p.
Keywords: fertilization
thinning
growth
yield
tree morphology
tree/stand health
Abstract:
Responses after 15 yr to 3 rates of nitrogen (urea),
applied at 0, 224 or 448 kg N/ha to a 24-yr-old Douglas fir (Pseudotsuga
menziesii) stand in the very dry maritime region of British Columbia, were analysed on the basis of per hectare, individual
tree, crop tree and tree size class. Thinned and unthinned plots were measured.
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51. Garman, S.L., J.H. Cissel and
J.H. Mayo. 2003. Accelerating development of late-successional conditions in
young managed Douglas-fir stands: a simulation study. Pacific-Northwest-Research-Station,-USDA-Forest-Service General-Technical-Report
PNW-GTR-557. ii
+ 57 p.
Keywords: thinning
commercial thinning
yield
Abstract: The
goal of this simulation study was to provide information for defining thinning
regimes for young Douglas-fir (Pseudotsuga menziesii) stands in the Central
Cascades Adaptive Management Area, located in west-central Oregon, USA. Specifically, this study used the ZELIG.PNW (3.0) gap
model to evaluate effects of experimental thinning treatments on the
development of late-successional attributes and on extracted merchantable
volume. Sixty-four thinning treatments were simulated for four rotation
intervals (260, 180, 100, and 80 years) starting with a 40-year-old managed
Douglas-fir stand. The amount of time for five late successional attributes to
reach defined threshold levels, long-term developmental trends of these
attributes, and amount of extracted merchantable volume were recorded for each
treatment. Stand conditions of selected treatments were used in a subsequent
harvest rotation in which 64 additional experimental thinning treatments were
applied and evaluated. A total of 1744 thinning treatments was
evaluated in this study. Results of this study confirm previous recommendations
for accelerating development of late-successional attributes in young managed
stands. Additionally, results show the potential for a range of thinning
treatments to attain late-successional conditions in about the same amount of
time, but with different trade-offs in terms of merchantable volume and
long-term stand conditions. In general, heavy thinning of existing stands at
ages 40 and 60 years promoted rapid development of large boles, vertical
diversity, and tree-species diversity, but provided the least amount of
extracted volume and required artificial creation of dead wood. Treatments that
retained more than 40% of the original overstorey and thinned to 99 trees per
hectare at age 60 delayed attainment of late-successional conditions by 10 to
30 years but provided 12 to 20% more extracted volume, resulted in higher
levels of most late-successional attributes at the end of a rotation, and
required less artificial creation of dead wood. Treatments providing the
fastest development of late-successional conditions in subsequent rotations
varied with the amount of canopy cover retained at the end of the first
rotation. For stands starting with <more or =>30% canopy cover, delaying
the first commercial thin for 40 years promoted the most rapid development of
vertical structure and shade-tolerant stems. Lower canopy-retention levels
required heavy or light thins in subsequent entries, depending on the rotation
interval, for rapid development of late-successional attributes.
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52. Gartner, B.L., J.J. Morrell, C.M.
Freitag and R. Spicer. 1999. Heartwood decay resistance by vertical and radial
position in Douglas-fir trees from a young stand.
Canadian-Journal-of-Forest-Research 29(12): 1993-1996.
Keywords: fertilization
thinning
wood quality
Abstract:
Heartwood durability of Douglas-fir (Pseudotsuga menziesii var. menziesii) was studied
as a function of vertical and radial position in boles of trees with a wide
range of leaf area/sapwood area ratios. Six 34-year-old trees were harvested
from each of three plots: very dense, thinned, and thinned and fertilized with
N, P, K, Ca, S and Fe (51, 11, 10, 7, 4 and 0.3 kg/ha, respectively),
established 14 years before at a site in the central Cascades of Oregon.
Heartwood samples from three radial positions and five heights were incubated
with the decay fungus Postia placenta [Oligoporus placenta]. There were no
significant differences in wood mass loss (decay resistance) by vertical or
radial position. One could expect that trees with high leaf area/sapwood area
could have the carbon to produce heartwood that is more resistant to decay than
trees with lower leaf area/sapwood area. However, no relationship was found
between leaf area above node 20, sapwood area there, or their ratio, and the
decay resistance of outer heartwood at that node. These results suggest that,
for young Douglas-fir trees, heartwood durability does not vary with position
in the bole or with environments that alter the balance of sapwood and leaf
area in a tree. It is suggested that young stands may thus be robust with
respect to the effect of silvicultural regimes on heartwood durability.
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53. Gartner, B.L., E.M. North, G.R.
Johnson and R. Singleton. 2002. Effects of live crown on vertical patterns of
wood density and growth in Douglas-fir. Canadian-Journal-of-Forest-Research
32(3): 439-447.
Keywords: thinning
pruning
wood quality
Abstract: It
would be valuable economically to know what are the biological triggers for
formation of mature wood (currently of high value) and (or) what maintains
production of juvenile wood (currently of low value), to develop silvicultural
regimes that control the relative production of the two types of wood.
Foresters commonly assume the bole of softwoods produces juvenile wood within
the crown and mature wood below. We tested that assumption by comparing growth
ring areas and widths and wood density components of the outer three growth
rings in disks sampled from different vertical positions of 34-year-old
Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees.
The 18 trees were sampled from one site and had a wide range of heights to live
crown. Most of the variance (63-93%) in wood characteristics (growth ring area:
total, earlywood, latewood; growth ring width: total, earlywood, latewood;
latewood proportion: by area, width; and ring density: total, earlywood,
latewood) was due to within-tree differences (related to age of the disk).
Stepwise regression analysis gave us equations to estimate wood
characteristics, after which we analysed the residuals with a linear model that
included whether a disk was within or below the crown (defined as the lowest
node on the stem with less than three live branches). After adjusting for tree
and disk position, only 2-10% of the residual variation was associated with
whether the disk was in or out of the live crown. There were no statistically
significant differences at p=0.05 between a given disk (by node number) in
versus out of the crown for any of the factors studied. Moreover, the wood
density characteristics were not statistically significant at p=0.30. This
research suggests that there was no effect of the crown position on the
transition from juvenile to mature wood as judged by wood density. Therefore,
we found no evidence to support the concept that tree spacing and live-branch
pruning have a significant effect on the cambial age of transition from
juvenile to mature wood in Douglas-fir trees of this age.
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54. Greene, S.E. and W.H. Emmingham.
1986. Early lessons from commercial thinning in a 30-year-old Sitka spruce-western hemlock forest. Pacific-Northwest-Research-Station,-USDA-Forest-Service Research-Note PNW-RN-448. 14 p.
Keywords: thinning
commercial thinning
growth
tree/stand health
tree morphology
Abstract: Three
commercial thinning treatments were applied to a 30-yr-old stand of Picea
sitchensis and Tsuga heterophylla with Pseudotsuga menziesii that had been
precommercially thinned at 15 yr old on the Oregon coast. Data were collected to determine the effects of
thinning on diam. and ht. growth, the amount of damage and subsequent decay in
remaining trees and relations between leaf area and volume production.
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55. Haight, R.G. 1993a. The economics of Douglas-fir and red alder management with
stochastic price trends. Canadian-Journal-of-Forest-Research 23(8):
1695-1703.
Keywords: planting operations
site preparation
prescribed fire
release treatments
chemical release
thinning
precommercial thinning
commercial thinning
tree/stand protection
economics
Abstract: A
financial analysis of Douglas fir (Pseudotsuga menziesii) and red alder (Alnus
rubra) management was conducted using yield projections from the Stand
Projection Simulator for the Pacific
Northwest region of the United
Sates. The analysis included uncertainty in the price trends and stocking
levels of both species following reforestation. Results from a case study in
which Douglas fir price is likely to increase faster than red alder price show
that (i) on more productive sites, greater regeneration investment is justified
to increase the likelihood of Douglas fir establishment, (ii) on less
productive sites, low-cost regeneration options that produce mixed-species
stands have expected present values close to or greater than a high-cost
Douglas fir regeneration effort, (iii) optimal precommercial removal of red
alder depends on mid-rotation prices and regeneration success, and in many
cases growing a mixed-species stand to maturity produces the highest economic
return, and (iv) commercial thinning of Douglas fir increases the expected
present value of the most intensive regeneration option by up to 10%. The
low-cost regeneration options have relatively high expected returns because of
low initial investments and the presence of two species that may have high
values in the future. The sensitivity of these results to changes in the
probability distributions of regeneration success and price trends is
discussed.
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56. Haight, R.G. 1993b. Technology change and the economics of silvicultural investment.
Rocky-Mountain-Forest-and-Range-Experiment-Station,-USDA-Forest-Service General-Technical-Report RM-GTR-232. ii + 18 p.
Keywords: planting operations
site preparation
prescribed fire
release treatments
chemical release
tree/stand protection
thinning
commercial thinning
precommercial thinning
yield
economics
Abstract: Financial
analyses of intensive and low-cost reforestation options are conducted for loblolly
pine (Pinus contorta) stands with broadleaved competition in the Southern USA,
and Douglas fir with red alder (Pseudotsuga menziesii with Alnus rubra) in the
Pacific Northwest. Results show that the expected present values (EPVs) of
low-cost options that result in mixtures of conifers and broadleaves are
superior in some situations to the EPVs of the intensive options.
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57. Hall, T.H., R.V. Quenet, C.R.
Layton and R.J. Robertson. 1980. Fertilization and thinning effects on a
Douglas-fir ecosystem at Shawnigan Lake: 6 year growth response. Pacific-Forest-Research-Centre,
Canadian Forestry Service Information-Report BC-X-202. 31 p.
Keywords: fertilization
thinning
growth
Abstract: Further
results are given for this stand in British Columbia at 30 yr old [see FA 43, 1945]. Gains in gross vol. increment
(over control at 24 yr old) for the 200 initially largest trees/ha were 20% for
heavy thinning alone, 51% for heavy fertilizer (urea) application alone and
139% for heavy thinning plus heavy fertilizer application. Adjustments by
covariance analysis for differences in intitial stocking and tree size
distributions gave values of 47, 76 and 139% respectively.
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58. Han, H., L.D. Kellogg, G.M. Filip
and T.D. Brown. 2000. Scar closure and future timber value losses from thinning
damage in western Oregon. Forest-Products-Journal 50(1): 36-42.
Keywords: thinning
tree/stand health
economics
Abstract: This
study investigated bark growth and decay development after thinning damage at
two western Oregon sites, and estimated value loss with a tree growth model.
All scars that remained open in western hemlock (Tsuga heterophylla) and Sitka spruce (Picea sitchensis) had advanced decay 13 years
after initial wounding. Scars less than 4 inches wide closed in 8 years.
Douglas-fir (Pseudotsuga menziesii) was more resistant to decay; no rot was
observed in scars less than 21 years old. Advanced decay and pitch rings,
however, were observed in 29-year-old scars, both open and closed. Because of
these defects, future value loss increased with time after wounding and with
higher stand damage levels. Fifty years after thinning, about 2% of the total
future log value, or $189/ac. (1997$), could be lost in Douglas-fir stands with
20% stand damage and a 2-inch diameter deduction. This loss could be reduced to
$58/ac. if stand damage were minimized to 5% with more careful techniques. The
increase in thinning costs ($61/ac. for tractor thinning; $79/ac. for
cut-to-length; $124/ac. for skyline; with a 5% increase in production time)
that is incurred while trying to minimize stand damage could be justified if it
reduced future value losses to crop trees.
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59. Harper, P.A. and A.S. Harestad.
1986. Vole damage to coniferous trees on Texada Island. Forestry-Chronicle 62(5): 429-432.
Keywords: thinning
precommercial thinning
tree/stand protection
tree/stand health
growth
Abstract:
Microtus townsendii injured trees by removal of bark and cambium from stems,
branches and roots of Douglas fir, western hemlock and, rarely, Pinus monticola
on Texada Island, British
Columbia. Damage
occurred more frequently in precommercially thinned stands <40 yr old than
in unspaced stands. Trees with d.b.h. <less or =>19 cm were damaged by
voles, but there was no selection by diam. or age class. No trees of ht. >16
m were damaged. For trees <16 m, damage increased as ht. decreased. There were n.s.d. in growth rates of trees damaged by voles when
comparing the 2-yr av. before spacing and vole damage with the av. after these
events. Stands should continue to be monitored to evaluate long-term effects of
vole damage. On the basis of these results, control of voles is not
recommended.
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60. Heath, L.S. and H.N. Chappell.
1989. Growth response to fertilization in young Douglas-fir stands. Western-Journal-of-Applied-Forestry
4(4): 116-119.
Keywords: fertilization
thinning
growth
Abstract:
Response surface methodology was used to estimate 6-yr vol. growth response to
1 application of 200 lb N/acre in unthinned and thinned Douglas fir (Pseudotsuga
menziesii) stands of b.h. age <less or =>25 yr in W. Washington and W.
Oregon. Regional mean fertilizer response was 16% in unthinned stands and 20%
in thinned stands. Site index had an increasingly inverse effect on response as
b.a. increased in both unthinned and thinned stands.
Response varied little over site index in regions of low b.a.,
decreased moderately as site index increased in the intermediate region, and
decreased rapidly in the high b.a. region.
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61. Henry, C.L., D.W. Cole, T.M.
Hinckley and R.B. Harrison. 1993. The use of municipal and pulp and paper
sludges to increase production in forestry. Journal-of-Sustainable-Forestry
1(3): 41-55.
Keywords: nursery operations
nursery fertilization
fertilization
thinning
growth
tree/stand health
soil properties
Abstract: Because
of their high nutritional content and soil conditioning properties, municipal
and pulp and paper (P&P) sludges (biosolids) can serve as soil amendments
for nutritionally deprived or organically poor soils on forest sites. Studies
conducted over the past 20 years at an experimental forest site in Western
Washington, USA, have largely confirmed the potential of biosolids to
increase the productivity of many forest lands. These studies clearly
demonstrated that application of biosolids at environmentally acceptable rates
will result in growth responses for both young seedlings as well as established
stands. Municipal biosolids have been applied to a number of Douglas fir
(Pseudotsuga menziesii) stands. Young stands treated with 47 t/ha showed an
average of 72, 14 and 2% height responses for Site Class IV, III and II,
respectively, over a 10 year period. Thinned versus unthinned 55-year-old
Douglas fir treated with 142 dry t/ha averaged 43 and 48%, respectively, for
the 12 year period greater than controls. Average growth responses of 65 and
40% occurred in the 65-year-old stand for the Site Class IV and II,
respectively, from a 47 dry t/ha application. Growth response resulting from
application of P&P biosolids to a number of tree species (Douglas fir,
Pinus monticola and Abies procera in nursery beds, and plots of Populus
deltoides x P. trichocarpa rooted cuttings) has also been excellent. When
properly applied, biosolids can provide an excellent alternative to chemical fertilizers
as a means of enhancing forest production. Growth response is typically greater
and lasts longer when compared with chemical fertilizers.
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62. Hermann, R.K. and D.P. Lavender.
1999. Douglas-fir planted forests. New-Forests 17(1/3): 53-70.
Keywords: genetic tree improvement
nursery operations
planting operations
site preparation
release treatments
fertilization
thinning
pruning
tree/stand protection
growth
yield
Abstract: A combination
of superior wood quality and high productivity has made Douglas fir
(Pseudotsuga menziesii) one of the premier timber trees in the world. As such,
it is grown as a plantation species in several countries in Europe and South America,
and in New
Zealand and
Australia, as well as throughout its extensive natural range in
western North America. Decades of experience with the silviculture of young
stands have demonstrated that practices such as planting, the use of
genetically improved seedlings, precommercial and commercial thinning, and
fertilizing may dramatically increase the yield of industrial products over
that of natural forests. Further, such silviculture is compatible with the
production of desired amenities. Vigorous implementation of such practices
wherever Douglas fir is cultivated will increase the world's timber resources,
and be an effective strategy for reducing the pressure, occasioned by the
world's rapidly increasing population, to harvest the fragile tropical and
boreal forests.
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63. Hessburg, P.F., D.J. Goheen and
H. Koester. 2001. Association of black stain root disease with roads, skid
trails, and precommercial thinning in Southwest Oregon. Western-Journal-of-Applied-Forestry 16(3): 127-135.
Keywords: thinning
precommercial thinning
tree/stand protection
tree/stand health
Abstract: The
incidence and severity of black stain root disease (BSRD), caused by
Leptographium wageneri, were evaluated in a two-stage
sample of 500 precommercial-aged Douglas-fir (Pseudotsuga menziesii)
plantations on 5 Resource Areas of the Medford District, Bureau of Land
Management in Oregon, USA. Black stain was widely distributed throughout the western
half of the District. Nearly 19% of the susceptible-aged (10- to 30-year-old)
plantations were infected with black stain, but mortality losses were low. In
both the extensive and intensive surveys, BSRD was more often distributed in
precommercially thinned than unthinned plantations. Black stain occurred with
significantly greater frequency adjacent to roads and major skid trails than in
the main body of plantations. Roadside strips displayed significantly more
injured trees and recent soil disturbance than the main body of plantations.
BSRD incidence was high in comparison with other root diseases, but there was
minimal impact to precommercial stand management. Low disease severity is
somewhat unique among managed forests within this area of known high BSRD
hazard. The lack of widespread damage from BSRD was associated with a lack of
extensive tractor yarding and an apparent lack of precommercial thinning. Forest managers within high BSRD hazard areas can maintain low
mortality levels by minimizing site disturbance and tree injury associated with
timber harvesting, road building, and road maintenance activities and by timing
precommercial thinning to avoid vector insect emergence and flight periods.
Increased disturbance and injury to precommercial-aged stands will likely
result in increased disease.
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64. Hong, S. and J.J. Morrell. 1997.
Treatability of Douglas-fir heartwood with ACZA or CCA: effect on site,
silvicultural practice, and wood properties. Forest-Products-Journal 47(10):
51-55.
Keywords: planting operations
fertilization
thinning
wood quality
Abstract: The effects
of site, silvicultural treatments, and wood properties on treatability of
Douglas-fir (Pseudotsuga menziesii) heartwood, from Washington and Oregon, with chromated copper arsenate (CCA) or ammoniacal copper
zinc arsenate (ACZA) were studied. Thinning appeared to be associated with
slight improvements in treatability (penetration and retention of
preservative), but combinations of thinning and fertilization had no
significant effect on this property. Other factors such as site, height from
which the sample was removed, and percentage of juvenile wood had inconsistent
effects on treatability. Although the results indicate that silvicultural
practices have minimal effects on treatability of Douglas-fir, further studies
are required to clarify these effects.
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65. Huffman, D.W. and J.C. Tappeiner,
II. 1997. Clonal expansion and seedling recruitment of Oregon grape (Berberis
nervosa) in Douglas-fir (Pseudotsuga menziesii) forests: comparisons with salal
(Gaultheria shallon). Canadian-Journal-of-Forest-Research 27(11): 1788-1793.
Keywords: thinning
stand conditions
Abstract: Seedling
regeneration and morphology of Oregon grape (Berberis nervosa) and salal
(Gaultheria shallon) were studied in thinned and unthinned Douglas fir
(Pseudotsuga menziesii) stands in the central Coast Range, Oregon. Above- and below-ground growth of both
species were significantly and negatively correlated with stand density.
Oregon grape appears to have less potential for vegetative spread than does
salal. It produced two to three times fewer rhizome extensions, and rhizome
extensions were only half as long as those of salal. Oregon grape seedlings
were common in areas of moss ground cover among patches of the two species.
Salal seedlings were restricted to decaying logs. Seedling densities of Oregon
grape in thinned stands were more than six times those in unthinned stands. For
Oregon grape, understorey establishment is accomplished by seedling
establishment and recruitment of new genets. In contrast, salal maintains
itself in forest understories primarily through vegetative growth, since its
seedling establishment is restricted mainly to decayed wood. Continual
recruitment of new aerial stems or ramets enables Oregon grape to maintain a
dense cover once it is established in the understorey.
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66. Huffman, D.W., J.C. Tappeiner, II
and J.C. Zasada. 1994. Regeneration of salal (Gaultheria shallon) in the
central Coast Range forests of Oregon. Canadian-Journal-of-Botany 72(1): 39-51.
Keywords: thinning
stand conditions
Abstract: Regeneration
of salal (Gaultheria shallon) by seedling establishment and vegetative
expansion was examined in Douglas fir (Pseudotsuga menziesii) stands that had
been thinned, clear felled or undisturbed in the central Coast Range of Oregon.
Size and expansion rate of individual clonal fragments were negatively
correlated with overstorey stand density (p <less or =>0.039). As
overstorey basal area increased from 25 to 75 msuperscript 2/ha, mean annual
growth percentage of clone rhizome systems decreased from 23.7 to 0% and mean
total rhizome length decreased from 102 to 0.89 m. Interclonal competition in
dense clumps of salal apparently caused rhizomes to die and clones to fragment.
In these patches, rhizome biomass and density, aerial stem biomass and density,
and total biomass of G. shallon were negatively correlated with overstorey
density (p <less or =>0.01). In clear fellings, salal clumps had up to
177.7 m rhizome/msuperscript 2 and 346 stems/msuperscript 2, whereas patches
under dense overstories had as few as 10.6 m rhizome/msuperscript 2 and 19
stems/msuperscript 2. Aerial stem populations had uneven-age distributions in
all overstorey densities. This structure is apparently maintained through
annual production of new ramets. Salal seedling establishment rates were
significantly affected by study site location, overstorey density, and
substrate (p <less or =>0.05). Two-year survival was highest on rotten
logs and stumps in thinned stands.
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67. Hummel, S. and R. Hummel. 2004.
Five-year thinning response of an overgrown Douglas-fir Christmas tree
plantation. Western-Journal-of-Applied-Forestry 19(3): 171-174.
Keywords: planting operations
thinning
growth
yield
economics
Abstract: A
15-year-old Douglas-fir Christmas tree plantation in western Oregon was thinned in 1996 according to regional sawtimber
conversion guidelines. The plantation comprised two strata, distinguished by
initial planting density (Area 1=5x5 ft and Area 2=10x10 ft). Unthinned control
plots were established in both Area 1 and Area 2 at the time of the thinning
treatment. Five years later, the quadratic mean diameter (QMD) in Area 1
(thinned) was 6.4 in. versus 5.2 in. in Area 1 (unthinned), while in Area 2
(thinned) the QMD was 11.4 in. compared to 9.3 in. in Area 2 (unthinned). Over
the same period, the volume/ac in Area 1 (thinned) (1,080 ft3/ac) was nearly
twice that of Area 1 (unthinned) (576 ft3/ac). In
contrast, the volume/ac in Area 2 (thinned) (2,318 ft3/acre) was almost half
that of Area 2 (unthinned) (4,264 ft3/ac). These
results suggest that while thinning was timely for Area 1, the thinning
treatment could have been delayed for Area 2. By plantation age 30, the treated
units in Area 1 and Area 2 have estimated yields of 9.6 and 11.6 thousand bd ft
(mbf), respectively, with no additional thinning. Given 2002 average prices for
#3 sawmill grade logs, gross return at age 30 would
range between $5,000 and $6,000/ac.
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68. Hunt, J.A. 1995. Commercial thinning a
coastal second-growth forest with a Timberjack cut-to-length system. Forest-Engineering-Research-Institute-of-Canada FERIC TN-235.
14.
Keywords: thinning
commercial
thinning
economics
tree/stand
health
Abstract: In the
summer of 1994, after 2 years operation, FERIC monitored a thinning operation
of second-growth forest dominated by Douglas fir [Pseudotsuga menziesii] near Cowichan
Lake, Vancouver
Island, to determine
productivities, costs and impacts to sites and residual stands. The thinning
treatment was carried out with a Timberjack 1270 harvester and a Timberjack 910
forwarder.
Non-OSU
Link
69. Jozsa, L.A.
and H. Brix. 1989. The effects of fertilization and thinning on wood quality of
a 24-year-old Douglas fir stand. Canadian-Journal-of-Forest-Research 19(9):
1137-1145.
Keywords: fertilization
thinning
wood quality
growth
Abstract:
The effect of thinning and N fertilization on growth and wood density
of coastal Douglas fir (Pseudotsuga menziesii) on a poor site on Vancouver
Island (British Columbia)
is described for plots established at approx. 24 yr old in 1971-72. Stem cores
were taken using an increment borer in Mar.-Apr. 1984. Ring-width and
ring-density data were obtained from pith to bark for all trees using
computerized X-ray densitometry. Fertilization reduced ring density at b.h. and
25% stem ht. by an av. of 6% for a 3- to 4-yr period after treatment, but not
thereafter. Reductions in ring density resulted from decreases in the density
of earlywood and latewood, as well as from decreases in latewood percentages.
Effects were only pronounced in the lower half of the stem. Thinning resulted
in a slight increase in ring-density in the lower bole and a reduction in the
top. The combined treatments had an intermediate effect on ring density. Ring
density showed an increasing trend from pith to bark at all ht. except at 75%
stem ht., and a decrease with increasing ht. in the
bole. Fertilization and thinning both increased diam. growth, and the
beneficial effects were still evident 13 yr after treatments.
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70. Kellogg, L.D., G.V. Milota and M. Miller, Jr. 1996. A comparison of skyline harvesting costs for alternative commercial
thinning prescriptions. Journal-of-Forest-Engineering 7(3): 7-23.
Keywords: thinning
commercial thinning
economics
Abstract:
Harvesting production and costs were examined for three alternative
silvicultural prescriptions at two sites in the Coast Range of Oregon, USA.
Thirty-three-year-old Douglas fir (Pseudotsuga menziesii) stands were
commercially thinned to residual densities of 247, 148, and 74 trees per
hectare (tph). Detailed time studies were conducted on manual felling and
uphill skyline yarding with small yarders. Separate regression equations were
developed to predict delay-free felling cycle time and delay-free yarding cycle
time. The 74 tph treatment had the highest production rate and was the least
costly to harvest. Total harvesting costs of the other two treatments averaged
from 6.0% (148 tph) to 12.3% (247 tph) more than the 74 tph treatment.
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71. Kellogg, L.D., G.V. Milota and B. Stringham. 1998. Logging
planning and layout costs for thinning: experience from the Willamette
young stand project. Forest-Research-Laboratory Research
Contribution 20, Oregon-State-University, Corvaliis, OR.
Keywords: thinning
commercial thinning
economics
Abstract:
Logging planning and layout costs were examined for commercial
thinning of 40- to 50-yr-old stands of Douglas-fir (Pseudotsuga menziesii) on
the Willamette National
Forest in the Cascade Mountains of Oregon. The
study consisted of four replications of three silvicultural treatments.
Thinning involved three types of logging systems: mechanized cut-to-length (a
combination of single-grip harvester and forwarder), tractor, and skyline. Data
for the study came from two sources: activities completed by the Forest Service
in preparing sales for bid, and the layout completed by the logging contractor
after a contract was awarded. Planning and layout costs showed no consistent
relationship to type of silvicultural treatment. Logging contractor layout
costs showed a relationship to type of logging system: the mechanized system
had the lowest layout cost, followed by the tractor systems, with the skyline
systems having the highest costs.
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72. Kimball, B.A., E.C. Turnblom, D.L. Nolte, D.L. Griffin and R.M.
Engeman. 1998b. Effects of thinning and nitrogen fertilization on sugars and
terpenes in Douglas-fir vascular tissues: implications for black bear foraging.
Forest-Science 44(4): 599-602.
Keywords: fertilization
thinning
tree/stand protection
tree physiology
tree/stand health
Abstract:
Analyses of vascular tissue samples from Douglas fir (Pseudotsuga menziesii)
trees collected in test plots in W. Washington and NW
Oregon, USA,
showed that both thinning and N fertilizer application caused the sugar
concentration of vascular tissues in the lower bole to increase. However, these
treatments had no effect on the concentrations of hydrocarbon monoterpenes,
oxygenated monoterpenes or sesquiterpenes. These results may explain the
observations that black bears (Ursus americanus) prefer to forage in thinned
and fertilized stands, as the bears maximize sugar intake and minimize terpene
intake while foraging.
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73. King, J.E., D.D. Marshall and J.F. Bell. 2002.
Levels-of-growing-stock cooperative study in Douglas-fir: report no. 17 - the
Skykomish study, 1961-93; the Clemons study, 1963-94. Pacific-Northwest-Research-Station,
USDA-Forest-Service Research-Paper PNW-RP-548. vii
+ 120 p.
Keywords: thinning
commercial thinning
growth
yield
tree/stand health
Abstract:
A study was conducted at the Skykomish Tree Farm, and at the Clemons Tree Farm,
Washington, USA,
to determine how the amount of growing stock in repeatedly thinned stands of
Douglas Fir (Pseudotsuga menziesii) affects cumulative
wood production, tree size and growth-growing stock ratios. Initial stands were
thinned to the same level of growing stock so that all plots would have
virtually the same growth potential except the unthinned controls. The
Skykomish and Clemons stands were 24 and 19 years old, respectively, when the
studies were started. Stand treatments were completed at ages 42 and 36, and
measurements were continued to ages 56 and 50. After 32 years at Skykomish and
31 years at Clemons, the basal area per acre in the eight regimes ranged from
119-244 ft2 at Skykomish and 101-195 at Clemons. The corresponding gross yields
in cubic feet per acre were 8709-13 579 at Skykomish and 6329-9072 at Clemons. Volume in thinnings were 18-53% of the gross yield. Stand
treatments included four regimes with different combinations of heavy and light
thinning and four regimes with constant intensities of thinning. Variable
regimes were found to have consistent advantage over constant regimes. Within a
given level of growing stock, the constant regimes are recommended for
applications where wood production is the primary objective. A substantial
increase in the yield was produced in all regimes during the post thinning
holding period. Based on standing volume after the last thinning, the holding
period of 4 years produced approximately 30% more volume in all regimes.
Extending the period to 9 years produced approximately 70% more volume, and at
14 years, the standing volume was more than double the volume remaining after
the last thinning. This extra yield enhanced by the high quality of the stands
makes the length of the holding period an important factor in the scheduling of
final harvest.
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74. Kramer, H. and J.H.G. Smith. 1985. Establishment of Douglas fir
stands in British Columbia.
Forstarchiv 56(1): 9-13.
Keywords: planting
operations
thinning
pruning
growth
yield
economics
wood quality
Abstract:
Square spacing trials were established NW of Haney (180 m alt.) at
0.91, 1.83, 2.74, 3.66 and 4.57 m. Growth to age 25 yr, and simulation
estimates up to 100 yr are reported. Results indicated that extra costs
(incurred by thinning) of stands closer than 4 m spacing are difficult to
justify in economic terms, because the market for Douglas fir timber grown in
British Columbia is such that only production of large timber is economically
viable. The quality of timber from trees grown at wide spacing without thinning
is acceptable in relation to Canadian requirements, and could be improved if
wide spacing were combined with pruning. It is recommended that close spacings
be used only if availability of land is limited or demand for biomass is very strong.
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75. Latham, P. and J. Tappeiner. 2002. Response of old-growth conifers
to reduction in stand density in western Oregon
forests. Tree-Physiology 22(2/3): 137-146.
Keywords: thinning
commercial thinning
growth
Abstract:
The positive growth response of healthy young trees to density reduction is
well known. In contrast, large old trees are usually thought to be
intrinsically limited in their ability to respond to increased growing space;
therefore, density reduction is seldom used in stands of old-growth trees. We
tested the null hypothesis that old-growth trees are incapable of responding
with increased growth following density reduction. The diameter growth response
of 271 Douglas-fir (Pseudotsuga menziesii), ponderosa pine (Pinus ponderosa)
and sugar pine (Pinus lambertiana) trees in Oregon, USA, ranging in age from 158 to 650
years was examined 20 to 50 years after density reduction. Density reduction
involved either light thinning with removal of less vigorous trees, or
shelterwood treatments in which overstorey trees were not removed. Ratios of
basal area growth after treatment to basal area growth before treatment, and
several other measures of growth, all indicated that the old trees sometimes
benefited and were not harmed by density reduction. Growth increased by 10% or
more for 68% of the trees in treated stands, and nearly 30% of trees increased
growth by over 50%. This growth response persisted for at least 20 years.
During this 20-year period, only three trees in treated stands (1.5%) exhibited
a rapid decrease in growth, whereas growth decreased in 64% of trees in
untreated stands. The length of time before a growth response to density
reduction occurred varied from 5
to 25 years, with the greatest growth response often occurring 20 to 25 years
after treatment. These results have important implications both for the basic
biology of aging in woody plants as well as for silvicultural practices in
forests with old-growth trees.
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76. LeDoux, C.B., R.D. Fight and T.L. Ortman. 1986. Stump-to-truck
cable logging cost equations for young-growth Douglas-fir. Western-Journal-of-Applied-Forestry
1(1): 19-22.
Keywords: thinning
commercial thinning
economics
Abstract:
Data on log sizes were generated to simulate young (age 40-120 yr) Douglas fir
site III and IV in the Pacific Northwest. The data were
used to develop equations for estimating the delay-free costs of: (1) felling,
limbing and cross-cutting; (2) yarding; (3) loading; (4) road changing; and (5)
moving in and out and initial rigging up and down. An additional equation
estimates the number of logs per 1000 ftsuperscript 3 for logs of d.b.h. 6-24
inch. The equations were developed for 2 small and 1 medium sized yarders and
are applicable on slopes of 10-50%. The equations can be used to provide
detailed estimates for thinning, partial or shelterwood felling and
clearfelling. A BASIC computer program is available from the authors.
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77. Lee, Y.J. and H.J. Barclay. 1985. Ten-year
growth response of a 25-year-old and a 55-year-old Douglas-fir stand to
thinning and urea fertilization. Pacific-Forestry-Centre,
Canadian-Forest-Service Information-Report BC-X-260. 14
p.
Keywords: fertilization
thinning
growth
tree/stand health
Abstract:
In stands of medium site quality in British Columbia,
4 rates of nitrogen (0, 112, 224, and 336 k/ha of N), in the form of urea (46%
N), were tested at two thinning intensities. Fertilizer was applied in spring
or fall, but the season of application had little effect on growth. Thinning
almost doubled diam. growth by 10 yr but affected only net vol. growth; gross vol.
was only minimally affected by thinning. Fertilization in the 25-yr-old stand
increased mean d.b.h. growth significantly in the second and third yr and
increased vol. growth significantly in the first 3 yr, but the effect
diminished thereafter. Different rates of fertilizer application on the
55-yr-old stand gave inconsistent results. Combined thinning and fertilizer
treatment had the greatest growth response. In both stands the overall effect
of 336 kg/ha N was to increase vol. growth by about 20%. Thinning significantly
decreased mortality, but the effect of fertilizer was negligible. Combined
treatment had the greatest effect on the advancement of trees by the number of
d.b.h. classes. The effect of thinning and fertilizing on the cumulative growth
will probably continue after 10 yr until crowding sets in.
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78. Maguire, D.A. 1994. Branch mortality and
potential litterfall from Douglas-fir trees in stands of varying density.
Forest-Ecology-and-Management 70(1/3): 41-53.
Keywords: thinning
wood quality
soil properties
Abstract:
Differential crown recession and crown development among stands of
differing density suggest that an opportunity may exist to control the input of
fine woody litter into the system by manipulating stand density. The objective
of this study was to measure the rate of branch mortality among stands of
differing density and to estimate the range in total per hectare necromass
inputs. Although litter traps are reliable for estimating per hectare rates of
litterfall, branch mortality dating on sectioned stems uniquely allows
assessment of several other litterfall components: (1) individual tree
contributions to total litterfall; (2) the amount of branch material released
by mortality, regardless of whether the branches are shed to the forest floor;
(3) the distribution of basal diameters characterizing the litterfall from a
given tree and stand. Twenty-four trees were felled and sectioned on permanent
plots that were part of a silvicultural study of Douglas fir (Pseudotsuga
menziesii) stand density regimes, in Umpqua National
Forest, near Tiller, Oregon. Whorl branches were dissected out of
bole sections to determine the dates of mortality, and a branch biomass
equation was applied to estimate potential rate of litterfall. Periodic annual
rates were expressed in four ways: (1) number of branches per tree; (2) mass of
branches per tree; (3) mass of branches per unit of crown projection area; (4)
mass of branches per hectare. For the growth periods investigated, larger trees
and trees growing on denser plots tended to release a greater necromass through
branch mortality. Average branch basal diameter generally decreased with
increasing stand density. Annual branch mortality ranged from 33 to 430 g m-2
crown projection area for individual trees, and from 236 to 1035 kg ha-1 for
individual plots. These rates approached the low end of the range of previously
published fine litterfall rates for Douglas fir. Rates on these plots were
relatively low owing to the temporary delay in crown recession imposed by
artificial thinning. A conceptual model of branch litter dynamics is presented
to depict consistencies with crown development among stands managed under
different density regimes.
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79. Maguire, D.A. and W.S. Bennett. 1996. Patterns in vertical
distribution of foliage in young coastal Douglas-fir.
Canadian-Journal-of-Forest-Research 26(11): 1991-2005.
Keywords: thinning
precommercial thinning
tree morphology
Abstract:
Variation in foliage distribution was analysed on trees and plots in a
series of even-aged Douglas fir (Pseudotsuga menziesii) stands scheduled for
management under a wide range of silvicultural regimes in British
Columbia, Washington
and Oregon. Branch-level foliage
mass and foliage area equations were developed from a sample of 138 branches.
These equations were applied to 27 trees on which the diameter and height of
all live primary branches were measured, allowing estimation of both the total
amount of foliage and its vertical distribution. A beta -distribution was
fitted to data describing the vertical distribution of foliage on each tree,
and the resulting parameter estimates were modelled as functions of tree
height, diameter at breast height, crown length, and relative height in the
stand. Foliage area distribution tended to be shifted downward relative to
foliage mass because of the expected increase in specific leaf area with depth
into the crown. Similarly, the relative foliage distribution in terms of both
mass and area was shifted downward as the tree became more dominant, or as
relative height in the stand increased. In contrast, foliage on trees of
similar relative height was shifted upward in response to the lower stand
densities imposed by precommercial thinning. On the stand level, relative
vertical distribution of foliage in the canopy was more peaked than would be
implied by assuming a constant leaf area/sapwood area ratio throughout the
composite tree crowns. Between-stand variation in vertical foliage distribution
was dictated by differences in stand top height, height to crown base, and
number of trees per hectare.
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80. Maguire, D.A., J.A. Kershaw, Jr. and D.W. Hann. 1991. Predicting
the effects of silvicultural regime on branch size and crown wood core in
Douglas-fir. Forest-Science 37(5): 1409-1428.
Keywords: thinning
precommercial thinning
commercial thinning
wood quality
Abstract:
Three major determinants of wood quality (whorl frequency, branch size and
crown wood core) in Douglas fir (Pseudotsuga menziesii) were estimated from the
dynamics of crown structure in ORGANON, an individual-tree, distance-independent
growth model. Data for the model were collected from Douglas fir plots in SW Oregon. Branch whorl locations were estimated directly
from the height growth predictions assuming formation of one whorl per year.
Mean maximum branch diameter was predicted as crown base receded past each
whorl; branch diameter estimates were based on current depth of the whorl into
crown, tree diameter, stand relative density, and site index. Diameter of crown
wood core was established as diameter inside bark, also as crown base receded
past each branch whorl. This approach facilitated description of harvested log
distribution (40-ft butt logs) by various branch size, whorl frequency and
crown wood core indices. Based on projections of a 9-yr-old Douglas fir stand
to final harvest at 65 years, thinning precommercially to 121 trees/acre at 9
yr old resulted in a BD4 (mean of four largest branch diameters per log) of 2.5
inches, vs. 1.5 inches for the unthinned stand (484 trees/acre). When thinned to 121 trees/acre, approximately 55% of the volume/acre in
40-ft butt logs consisted of crown wood, as opposed to 30% at 484 trees/acre.
Responses to subsequent thinnings were less pronounced, but included larger
branches in the largest 80 trees/acre, and larger total crown wood percentages
for a given initial stand density. Thinning from below resulted in larger
average BD4 values and slightly greater crown wood percentages than
proportional thinning. Individual-tree growth models that contain a crown
recession component can easily be modified to predict crown wood core and
indices of branch size.
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81. Marshall, D.D. and R.O. Curtis. 2002. Levels-of-growing-stock
cooperative study in Douglas-fir: report no. 15 - Hoskins: 1963-1998. Pacific-Northwest-Research-Station,-USDA-Forest-Service Research-Paper
PNW-RP-537. 80 p.
Keywords: thinning
commercial thinning
growth
yield
tree/stand health
tree morphology
Abstract:
The cooperative levels-of-growing-stock (LOGS) study in Douglas-fir
(Pseudotsuga menziesii (Mirb.) Franco) was begun to study the relations between
growing stock, growth, cumulative wood production, and tree size in repeatedly
thinned stands. This report summarizes results from the Hoskins installation
through age 55. Growing stock has been allowed to accumulate for 19 years since
the last treatment thinning was applied in this high site class II natural
stand. Volume and diameter growth were strongly related to growing stock. Basal
area growth-growing stock relations were considerably weaker. Differences in
tree size and volume distribution were considerable. Culmination of mean annual
increment has not occurred for any of the treatments, although the control has
culminated for total stem cubic volume and is near culmination for merchantable
cubic volume. Only small differences are seen in growth percentages between
thinning treatments. Results demonstrate potential flexibility in managing
Douglas-fir to reach a range of objectives.
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82. Marshall, P.L. 1988. A decision analytic approach to silvicultural investment decisions.
Forest-Economics-and-Policy-Analysis-Research-Unit,
University-of-British-Columbia Working-Paper 110. 28
p.
Keywords: planting
operations
thinning
precommercial thinning
economics
growth
Abstract:
A brief review of the literature is presented on methods for achieving optimal
silvicultural decisions. The methods are generally computationally cumbersome
and difficult to convert to simpler approximations required for most
silvicultural decisions. An alternative method is presented and illustrated
with two examples. The method involves a simple decision analytic structure.
Projections were made for pure coastal Douglas fir Pseudotsuga menziesii for
several treatments using three previously published growth models. Present Net Worth (PNW) was used as the criterion for choosing the
treatment option and rotation age. The first example involved an initial
planting density decision. Three planting densities were considered, viz. (1)
2500, (2) 1100 or (3) 750 seedlings/ha. The second example involved the
decision to thin a 15-yr-old stand to a spacing
similar to that produced by (1). The options were: (a) no treatment; (b) thin
to 1100 stems/ha; and (c) thin to 500 stems/ha. The best strategy depended on
which growth model was used. The study showed that a simplified decision
analytic approach is a useful method to evaluate a decision, when aided by
several growth models.
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83. Marshall, P.L. 1989. The economic value of additional information about
treatment-response information for coastal Douglas-fir. Forest-Economics-and-Policy-Analysis-Research-Unit,
University-of-British-Columbia Working-Paper 121. 39
p.
Keywords: planting
operations
thinning
precommercial thinning
economics
growth
Abstract:
A simple decision analytic approach was applied to initial planting
density and precommercial spacing decisions for coastal Douglas fir (Pseudotsuga
menziesii) across a range of sites in British Columbia.
The range of biological response was represented by the output from 3 growth
and yield models. Recent production costs and product values were applied to
obtain value per hectare after delivery of logs to the mill. Future costs and
revenues were discounted at 4, 6 and 8%. The best decisions from each growth
model are presented by scenario. Limitations of the analysis and managerial
implications are discussed.
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84. Messier, C. and A.K. Mitchell. 1994. Effects of thinning in a
43-year-old Douglas-fir stand on above- and below-ground biomass allocation and
leaf structure of understory Gaultheria shallon. Forest-Ecology-and-Management
68(2/3): 263-271.
Keywords: thinning
stand conditions
Abstract:
Salal (Gaultheria shallon) was studied in an unthinned and a heavily thinned
(two-thirds of basal area removed) 43-yr-old Douglas fir (Pseudotsuga
menziesii) plot 6 yr after thinning at Shawnigan Lake on southern Vancouver
Island, British Columbia. The increase in both above- and below-ground
resources caused by thinning resulted in a smaller fine-root/leaf biomass ratio
in the thinned (1.2) than the unthinned (2.0) plot. The balance between the
production of fine-roots to acquire limited water and of foliage to acquire
limited light is suggested as an explanation for this shift in carbon
allocation from fine-root to leaf biomass between the two plots. The responses
of G. shallon to thinning are discussed in relation to its role as a competitor
for below-ground resources.
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85. Miller, M. and B. Emmingham. 2001. Can selection thinning convert
even-age Douglas-fir stands to uneven-age structures?
Western-Journal-of-Applied-Forestry 16(1): 35-43.
Keywords: thinning
commercial thinning
growth
yield
tree/stand health
regeneration
Abstract:
Uneven-age management of Douglas-fir (Pseudotsuga menziesii) stands can be used
to address aesthetic, wildlife habitat, biodiversity and sustainability
concerns, but there has been little long-term experience with this type of
management. To develop timely information on converting even-age stands to
uneven-age forests, we used retrospective stand reconstruction methods to
document harvest frequency, intensity and stand structural development at four
sites in western Oregon,
USA.
We studied stands managed by selection thinning and identified strategies for
creating and managing uneven-age forests. Selection thinning
benefited mid- and understorey trees and stimulated natural regeneration.
Although stand growth was less than expected from low thinning, growth per unit
of growing stock was similar to that in unmanaged stands. Douglas-fir often
dominated natural regeneration and had satisfactory vigour at stocking levels
about half that considered full stocking for even-age management, but good
growth of regeneration may require even lower overstorey stocking.
Shade-tolerant grand fir (Abies grandis) and western hemlock (Tsuga
heterophylla), however, were more abundant at higher stocking levels. Selection
thinning of young Douglas-fir (Pseudotsuga menziesii) stands can sometimes be
effective in promoting viable regeneration while providing regular income and
biodiversity. Because this was a retrospective study only, further, long-term
testing is necessary.
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86. Miller, R.E., G.W. Clendenen and D. Bruce. 1988. Volume growth and
response to thinning and fertilizing of Douglas-fir stands in southwestern Oregon. Pacific-Northwest-Research-Station,-USDA-Forest-Service General-Technical-Report
PNW-GTR-221. ii + 38 p.
Keywords: fertilization
thinning
growth
Abstract:
Data were collected from 114 thinning (felling 15-80% of initial basal
area) and/or fertilizer application (usually urea at 200 or 400 lb N/acre)
trials in naturally regenerated Douglas fir (Pseudotsuga menziesii) stands in
SW Oregon (111 stands) and N. California (3 stands). The data were used to
develop regression equations to estimate volume growth for a 10-yr period of
treated and untreated stands, aged 10-70 yr. The predictions for SW Oregon
(SWOR) were compared with other growth predictions including DFSIM, a
simulation model based on a broader, regional database. SWOR consistently
showed greater gross and net growth of untreated Douglas fir and showed greater
benefits of nitrogen fertilization, especially on poor quality sites and in
young stands in the subregion than did DFSIM. SWOR predicted reduced gross
volume growth during the 10 yr after thinning, faster recovery from early
thinning on good than on poor sites, and increased wood production after
nitrogen treatment in 70% of thinned and unthinned Douglas fir stands.
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87. Miller, R.E., E.L. Obermeyer and H.W. Anderson. 1999. Comparative
effects of precommercial thinning, urea fertilizer, and red alder in a site II,
coast Douglas-fir plantation. Pacific-Northwest-Research-Station,-USDA-Forest-Service Research-Paper
PNW-RP-513. ii + 25 p.
Keywords: fertilization
thinning
precommercial thinning
growth
yield
tree/stand health
soil properties
Abstract:
The number of red alder (Alnus rubra) trees retained with 300 Douglas-fir (Pseudotsuga
menziesii) per acre was varied on a high-quality site in coastal Oregon.
Alder densities of 0, 20, 40, and 80 per acre were tested. A fifth treatment
eliminated nitrogen-fixing alder, but substituted nitrogen fertilizer.
Treatment 6 had neither thinning nor alder control. Treatments were randomly
assigned within each of three blocks in a 9-year-old plantation. Stand density
was reduced within 15 of these 18 experimental units. Surplus conifers were
cut, but surplus red alder were controlled by the "hack-and-squirt"
method. Because numerous trees of other species regenerated naturally, combined
density of all species before thinning ranged from 1400 to 5700 trees per acre.
Subsequent 17-year change in number, average height, basal area, and volume of
Douglas-fir were compared. Retaining 20, 40, or 80 alder per
acre reduced numbers of associated Douglas-fir by about 10, 17, and 23 percent,
respectively. In pure Douglas-fir plots, gross volume growth was similar
for non-fertilized and fertilized plots, indicating no measurable benefits of
additional nitrogen. In mixed stands, red alder reduced yield of associated
Douglas-fir, but not yield of combined species. Similar comparisons are needed
at other locations, especially those with known nitrogen deficiency.
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88. Miller, R.E., J. Smith and H. Anderson. 2001. Detecting response
of Douglas-fir plantations to urea fertilizer at three locations in the Oregon Coast Range.
Pacific-Northwest-Research-Station,-USDA-Forest-Service Research-Paper
PNW-RP-533. 20 p.
Keywords: fertilization
thinning
growth
tree/stand health
Abstract:
Fertilizer trials in coast Douglas-fir (Pseudotsuga menziesii var. menziesii)
in the Oregon Coast Range (USA) usually indicate small and statistically
non-significant response to nitrogen (N) fertilizers. Inherently weak
experimental designs of past trials could make them too insensitive to detect
growth differences that actually exist. Ability to detect real differences
among treatments should be improved by having more than two replications per
treatment and by using covariance analysis to adjust observed treatment means
for unequal starting conditions among experimental treatments. To demonstrate
these assumptions, we used size at fertilizer application and a pre-fertilizer
application (calibration) period of growth as covariates when analysing data
from five coastal plantations at three locations: Toledo North, Toledo South
and Bone
Mountain. The trials had
three to six replications per treatment and calibration periods of 6 or 7
years. Nitrogen fertilizer (urea at 200 lb N/acre) was assigned randomly to
half the plots at each location when trees were 16 or 17 years old from seed.
Our objectives were to quantify 4- or 7-year response to N fertilizer and to
demonstrate practical means for detecting response. Effects of fertilizer
application on tree diameter and height, and on basal
area and volume growth per acre were estimated. Among the five non-thinned
plantations, observed gross basal area growth was changed by -2 to 13% in the 4
or 7 years after fertilizer application. In the thinned portion of one
plantation, there were few differences in response to fertilizer between
thinned and unthinned plots. Observed responses were increased substantially by
covariance analyses at some plantations but decreased at others. Random
assignment of three to six plots per treatment did not ensure balanced or comparable
plots for fertilized and non-fertilized treatments.
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89. Mitchell, A.K., H.J. Barclay, H. Brix, D.F.W. Pollard, R. Benton
and R. DeJong. 1996. Biomass and nutrient element dynamics in Douglas-fir:
effects of thinning and nitrogen fertilization over 18 years.
Canadian-Journal-of-Forest-Research 26(3): 376-388.
Keywords: fertilization
thinning
precommercial thinning
carbon allocation
tree physiology
growth
soil properties
Abstract:
The effects of thinning (two-thirds of basal area removed) and N fertilizer
(448 kg N/ha as urea) on biomass and nutrition of a 24-year-old Douglas fir
(Pseudotsuga menziesii) stand at Shawnigan Lake, British Columbia, were studied
over 18 years. At years 0, 9, and 18 after treatments, the aboveground biomass
and N, P, K, Ca, and Mg contents of stemwood, stem bark, foliage, and dead and
live branches were determined (kg/ha), and increments in these properties
(kg/ha per year) were calculated for the 0-9 and 9-18 year periods. Foliar
biomass was increased by both treatments during the first period and also by
thinning in the second period. Aboveground net primary production (ANPP) per
unit of foliage biomass (foliage efficiency) was increased by treatments in the
0-9 year period. The combined effects of increased foliage mass and foliage
efficiency resulted in increased total biomass production. Thinning and
fertilizer application increased the uptake of all elements except for P with
fertilizer. This increase may have contributed to the long-term increase in
stem growth. Retranslocation of elements before foliage shedding was important
for tree nutrition, but was not improved by fertilizer during the 9-18 year
measurement period. The efficiency of N use in dry matter production (ANPP/unit
of N uptake) was decreased by fertilizer. This implied that poor sites would
respond to fertilizer better than rich sites.
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90. Mitchell, K.J. and J.R. Cameron. 1985. Managed stand yield tables
for coastal Douglas-fir: initial density and precommercial thinning.
Ministry-of-Forests, British-Columbia
Keywords: planting
operations
thinning
precommercial thinning
growth
yield
Abstract:
Yield tables are presented for second growth stands of Pseudotsuga
menziesii, established naturally (4440 trees/ha) or planted with 300, 500, 750,
1110 or 2500 trees/ha in British Columbia.
Separate tables describe the development of stands thinned to 500 or 1100
stems/ha when 6 m tall. The yield tables were produced by a biologically
oriented tree and stand simulation model (TASS) calibrated to conform with the yield of remeasured plots.
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91. Mitchell, S.J. 2000. Stem growth responses in Douglas-fir and Sitka spruce following
thinning: implications for assessing wind-firmness.
Forest-Ecology-and-Management 135(1/3): 105-114.
Keywords: thinning
tree morphology
carbon allocation
growth
Abstract:
Diagnosing the stand hazard component of windthrow risk requires
evaluation of the 'acclimation' of trees to wind loads. Height-diameter ratio
is a commonly used indicator of relative wind-firmness. A sample of coastal
Sitka spruce (Picea sitchensis) and interior Douglas fir (Pseudotsuga
menziesii) trees, representing a range of initial slenderness, were sampled
from stands in British Columbia, Canada, which had very high densities (about
6000 and 23,000 stems/ha, respectively) prior to thinning. Annual height
increment, radial increment, allocation of radial increment along the bole, and
height-diameter ratio were reconstructed using stem analysis. Thinning
treatments affected growth responses compared to trees in control (unthinned)
stands: temporary reduced height increment, increased radial increment and
increased basal allocation contributed to a reduction in height-diameter ratio.
This reduction was most pronounced in trees which were initially more slender.
The reverse-S pattern of height-diameter ratio adjustment and the patterns of
growth allocation suggest a period of acclimative growth during which the trees
re-equilibrate with post-thinning wind loads. Observing the rate of stem form
adjustment could be useful in diagnosing wind-firmness when scheduling multiple
thinning entries in high-density stands.
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92. Morrison, D.J. and A.L.S. Johnson. 1999a. Annosus root disease in
pre-commercially thinned stands in coastal British
Columbia. Canadian-Forest-Service
Technology Transfer Note 20, Pacific-Forestry-Centre, Victoria, BC.
Keywords: thinning
precommercial thinning
tree/stand protection
tree/stand health
Abstract:
An outline is given of the strategic importance of Heterobasidion annosum,
detection and recognition, damage to roots, factors affecting infection and
colonization of stumps and management implications for spacing in juvenile
stands. The relative susceptibilities of different species were: Abies
amabilis>Picea sitchensis>Tsuga heterophylla>Pseudotsuga menziesii.
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93. Morrison, D.J. and A.L.S. Johnson. 1999b. Incidence of
Heterobasidion annosum in precommercial thinning stumps in coastal British Columbia.
European-Journal-of-Forest-Pathology 29(1): 1-16.
Keywords: thinning
precommercial thinning
tree/stand protection
tree/stand health
Abstract:
Coniferous stumps in 83 stands in coastal British
Columbia, Canada,
were sampled 3-5 years after precommercial thinning between 1981 and 1986. The
percentage of stumps and surface area colonized by H. annosum were determined
for 25 stumps of each species, in each 5-cm diameter class present in each
stand. There were significant differences among species in the percentages of
stumps and surface area colonized, with Douglas-fir (Pseudotsuga menziesii)
having the lowest values, amabilis fir (Abies amabilis) and Sitka spruce (Picea sitchensis) the highest and
western hemlock (Tsuga heterophylla) being intermediate. For each species, both
the percentage of stumps and surface area colonized increased with increasing
diameter. In stumps that were grafted to an adjacent tree, there was decreased
incidence of H. annosum for Douglas-fir and Sitka
spruce and increased incidence for western hemlock and amabilis fir. There were
trends in the percentage of stumps and area colonized for season of thinning
and biogeoclimatic subzones, with the values for most species decreasing as the
amount of precipitation increased. It is suggested that the increase in
inoculum can be minimized by thinning trees when less than 15 years old, by
cutting only trees less than 10 cm in diameter and by thinning during low risk
seasons.
Non-OSU Link
94. Morrison, D.J., M.D. Larock and A.J. Waters. 1986. Stump infection
by Fomes annosus in spaced stands in the Prince Rupert Forest Region of British
Columbia. Pacific-Forestry-Centre, Canadian-Forest-Service
Information-Report BC-X-285. 12 p.
Keywords: thinning
tree/stand
protection
tree/stand
health
Abstract:
Discs 3-5 cm thick were collected after removal of the top 5-10 cm
from stumps left by thinning 1-8 yr previously of 12- to 37-yr-old stands of 5
coniferous species, and the occurrence and area of surface colonization with F.
annosus [Heterobasidion annosum] were measured. Based on the % of stumps with
more than 10% of their area colonized, susceptibility decreased in the sequence
Abies amabilis, Picea sitchensis, Tsuga heterophylla, Pseudotsuga menziesii;
Pinus contorta was unaffected. Fewer stumps were colonized in a T.
heterophylla/A. amabilis stand thinned in winter than in an adjacent stand
thinned in late spring: the difference was attributed to effects on spore
populations of low temp. and heavy precipitation.
There was a significant correlation between % stump area colonized and % root
vol. colonized by H. annosum for A. amabilis and T. heterophylla. H. annosum
had spread from colonized roots on some excavated stumps to or into adjacent
roots of reserved trees.
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95. O'-Hara, K.L. 1988. Stand structure and growing space efficiency
following thinning in an even-aged Douglas-fir stand.
Canadian-Journal-of-Forest-Research 18(7): 859-866.
Keywords: thinning
commercial thinning
growth
tree morphology
carbon allocation
Abstract:
The growth of individual trees from four thinning treatments in a
64-yr-old Pseudotsuga menziesii stand in western Washington
was analysed to determine desirable residual stand structures after thinning.
Dominant and codominant trees had the highest individual tree stem vol. growth
rates over the previous 5 yr and accounted for most stand vol. growth in
thinned and unthinned stands. Two measures of growing space, crown projection
area and sapwood b.a. (a surrogate for leaf area),
were used to measure how efficiently individual trees used their growing space.
Crown classes were useful in characterizing growing space efficiency (vol.
growth per unit of growing space) only in the unthinned treatment. In thinned
treatments, tall trees with medium-sized crowns were most efficient, while in
the unthinned treatment tall trees with relatively large crowns were most
efficient. A large crown in an unthinned stand was comparable in size to a
medium-sized crown in a thinned stand. Results suggest growing space is not
limiting individual tree growth in thinned stands and that thinning to a
particular stand structure is more appropriate than thinning to a particular
stand density.
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96. O'-Hara, K.L. 1989. Stand growth efficiency in a Douglas fir
thinning trial. Forestry-Oxford 62(4): 409-418.
Keywords: thinning
commercial thinning
growth
carbon allocation
tree morphology
Abstract:
Stand growth efficiency (ratio of periodic stand volume growth to sapwood basal
area) was measured over 5 yr (1980-84) in a long term Douglas fir (Pseudotsuga
menziesii) thinning trial (established in 1957 at 36-yr-old, with 5 thinnings
over 23 yr) in coastal Washington,
USA. Sapwood
basal area - as a surrogate for leaf area - and volume growth were estimated in
two fifth-hectare plots from each of three thinning treatments, and from a
single fifth-hectare control plot. Stand growth increased with increasing
sapwood basal area. No distinct pattern of stand growth efficiency with sapwood
basal area was evident. Large differences in efficiency between plots of the
same treatment were found and were attributed to differences in stand
structure, or the arrangement of tree sizes.
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97. O'-Hara, K.L. 1990. Twenty-eight years of thinning at several intensities
in a high-site Douglas-fir stand in western Washington.
Western-Journal-of-Applied-Forestry 5(2): 37-40.
Keywords: thinning
commercial thinning
growth
yield
Abstract:
Results are presented of a 28-year thinning study of a dense (182-452
tree/acre) natural, second growth Douglas fir (Pseudotsuga menziesii) stand at
Delezenne, which compared 3 thinning treatments with an unthinned control.
Treatments were: an increasing basal area treatment; a constant basal area
treatment (of approximately 140 ftsuperscript 2/acre); a decreasing/increasing
reserve basal area treatment; and control plots, which were 35 to 37-years-old
with basal area 80-203 ftsuperscript 2/acre in 1957 when the tests were
started. Gross, net, and total recoverable periodic cubic volume increments of
the control treatment (10 396, 9108 and 16 092 ftsuperscript 3/acre,
respectively) were not significantly different from the highest yielding
treatment, which was the increasing reserve basal area thinning treatment
(8896, 8594 and 16 636 ftsuperscript 3/acre, respectively). These results, and
options for thinning schedules, are discussed; it is suggested that commercial
thinnings of dense or fully stocked plantations of Douglas fir may produce
similar results, that is, vigorous stands with rapid growth potential.
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98. O'-Hara, K.L. and C.D. Oliver. 1988. Three-dimensional
representation of Douglas-fir volume growth: comparison of growth and yield
models with stand data. Forest-Science 34(3): 724-743.
Keywords: planting
operations
thinning
growth
yield
computer modeling
Abstract:
Growth and yield estimates for unthinned stands from the Douglas fir
Stand Simulator (DFSIM) and the Tree and Stand Simulator (TASS) were used to
construct graphical three-dimensional representations of Douglas fir
(Pseudotsuga menziesii) stand growth on site index 44 m (50 yr). The
three-dimensional models used three variables: trees per hectare, b.h. age, and
either mean tree vol. or stand vol. The TASS and DFSIM models were in agreement
over most of their common range of age and number of trees. At wider spacings
and older ages, however, the volumes predicted by the DFSIM model exceeded
those predicted by the TASS model by as much as 25%. Comparisons of these
three-dimensional models to unthinned and thinned stand data from a site of
similar quality in the Delezenne thinning trial, Washington, found the models to be reasonably
accurate representations of unthinned stand growth. The thinned stands,
however, had greater mean tree and stand volumes than those indicated by the
TASS model for unthinned stands at similar spacings. Complete comparisons were
not possible with the DFSIM model because of its limited range of number of trees.
These results suggest that the TASS model, and to a lesser extent, the DFSIM
model may be underestimating the growth of widely spaced stands, or thinning
may actually increase the growth of thinned trees over that of trees which had
always grown at the post-thinning spacing.
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99. Oliver, C.D. and M.D. Murray. 1984. Stand structure, thinning
prescriptions, and density indexes in a Douglas-fir thinning study, Western Washington,
U.S.A.
Canadian-Journal-of-Forest-Research 13(1): 126-136.
Keywords: thinning
commercial thinning
growth
stand conditions
Abstract:
In a stand regenerated after logging in 1930, thinnings to set b.a. values were carried out in 1959, 1962, 1966, and 1970.
On each plot both large and small trees were removed since av. b.a. per tree was kept constant before and after thinning.
Volume growth varied greatly between plots of the same age, initial b.a., and site because of differences in stand structure.
Large trees on a plot grew more per tree and per b.a.
than small trees. Stand b.a., stand vol., number of
stems, or number of dominant and codominant trees were not closely related to
vol. growth/ha, although density indexes giving weight to larger trees showed
the closest relationship. The lack of a close relationship between stand
desnsity indexes and growth probably means the indexes do not uniquely define
structures; it does not necessarily mean that thinning will not increase volume
growth/ha. Volume growth/ha after thinning to a given b.a. will be greater and
probably more consistent if larger trees are left and enough time is allowed
for the stand to recover following thinning.
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100. Omule, S.A.Y. 1984. Results from a correlated curve trend
experiment on spacing and thinning of coastal Douglas fir. B.C.
Ministry-of-Forests Research-Note 93. ix + 22
p.
Keywords: thinning
precommercial thinning
growth
yield
tree/stand health
Abstract:
Plots were established in 1952 in 13-yr-old plantations and given a variety of thinning
treatments to produce post-thinning densities of 125-3000 stems/ha. Trees were
measured at intervals up to 1980. Analysis showed that diam., ht. and their
growth increased with decrease in density. Mortality, b.a.,
total vol. and b.a. growth decreased as density decreased. Stand merchantable
vol. was not affected by density except at extremes. Prolonged early
suppression appeared to reduce the ability of a stand to respond to subsequent
thinning in terms of b.a. and total vol.
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101. Omule, S.A.Y. 1988. Growth and yield 35 years
after commercially thinning 50-year-old Douglas-fir. B.C.
Ministry of Forests FRDA-Report 021. vi + 15 p.
Keywords: thinning
commercial thinning
growth
yield
tree/stand health
Abstract:
Remeasurement data over a period of 35 years from fourteen 0.2023-ha
permanent plots were analysed to determine the growth and yield effects of
commercially thinning 50-year-old Douglas fir (Pseudotsuga menziesii) stands on
a good site on Vancouver Island, British Columbia. Compared to unthinned
stands, the commercially thinned stands had: virtually the same total volume
gross annual increment, top height and top height increment; 12% more
potentially usable total volume yield (including thinnings); 18% less total
volume at final harvest age 86 yr; virtually the same crop tree (193 largest
diameter trees per hectare) average diameter, but 24% larger entire stand
quadratic mean diameter; and 11% less total volume production lost to
mortality. These results show that commercial thinning slightly increased total
stand yield (including thinnings) and produced larger stand diameter at
rotation age 86 yr, but that it also reduced usable total volume at final
harvest and had virtually no effect on size of the crop trees. Data from this
study are useful for validating growth models, and for constructing and
comparing managed stand yield tables for various commercial thinning regimes.
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102. Omule, S.A.Y. 1990. Net basal area response 9
years after fertilizing thinned and unthinned Douglas-fir. B.C. Ministry of Forests FRDA-Report 097. vi
+ 20 p.
Keywords: fertilization
thinning
growth
Abstract:
Equations were developed to estimate net basal area response of
Douglas fir (Pseudotsuga menziesii) to nitrogen (urea) fertilizer in terms of
initial stand attributes, based on remeasurement data over a 9-yr period from
176 plots on Vancouver Island, British
Columbia.
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103. Peterson, C.E. 1984. Fertilization of
Douglas-fir plantations in the Pacific Northwest RFNRP Cooperative. In
Proceedings IUFRO Symposium on Site and Productivity of Fast Growing
Plantations Volume 2, South African Forest Research Institute, Pretoria, South
Africa. Eds. D.C. Grey, A.P.G. Schonau and C.J. Schutz. pp. 637-645.
Keywords: planting
operations
fertilization
thinning
precommercial thinning
growth
Abstract:
Since 1975, the RFNRP cooperative has established 26 installations in
young widely spaced plantations of Douglas-fir for testing response to 224 kg-N/ha.
These plantations ranged in breast-height age from 3 to 23 years, and although
response to fertilization was favorable in all Douglas-fir plantations, those
which were spaced to 1000 trees/ha responded significantly better than
plantations of 725 trees/ha, in both absolute and relative 2-year basal area
increment (msuperscript 2 ha-1 year-1). Response also appears to be greater
when fertilizer was applied 2 years after precommercial thinning, as opposed to
fertilizing and thinning at the same time. The relationship of growth response
with stocking level is discussed, as well as the timing of fertilization
relative to spacing, in young Douglas-fir plantations.
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104. Peterson, C.E. and J.W. Hazard. 1990. Regional variation in
growth response of coastal Douglas-fir to nitrogen fertilizer in the Pacific Northwest. Forest-Science 36(3): 625-640.
Keywords: fertilization
thinning
growth
Abstract:
Hypothesis-testing for differences in growth responses among
physiographic strata, thinning levels, and fertilizer
dosage levels resulted in a set of empirical models for predicting the volume
increment response of even-aged coastal Douglas fir (Pseudotsuga menziesii) in W.
Washington and Oregon
to N fertilizer treatment. Absolute and percentage responses are estimated for
both thinned and unthinned stands as a function of dosage levels and
physiographic provinces. Although not 'highly' significant, the physiographic
factor was retained in the models for purposes of refinement.
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105. Peterson, C.E., P.J. Ryan and S.P. Gessel. 1984. Response of
northwest Douglas-fir stands to urea: correlations with forest soil properties.
Soil-Science-Society-of-America-Journal 48(1): 162-169.
Keywords: fertilization
thinning
growth
soil properties
Abstract:
Replicated forest floor and surface soil (0-15 cm) samples were
obtained from control plots at 160 field installations in western Washington
and Oregon. Six-year growth
responses of thinned and unthinned Douglas-fir [Pseudotsuga menziesii] treated
with 0, 224, and 448 of urea-N ha-1 were correlated with 18 forest floor and
surface soil properties of the control plots. Forest
floor nitrogen properties were the most highly correlated with various
estimates of response in both thinned and unthinned stands; these correlations
were generally independent of methods used to estimate response. For unthinned
stands, C/N ratios of both forest floor and surface soil were well correlated
with growth response to fertilizer, whereas for thinned stands, N content
(kilograms per hectare) of the forest floor was consistently correlated with
response.
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106. Pilkerton, S.J., H. Han and L.D. Kellogg. 1996. Quantifying
residual stand damage in partial harvest operations. In Planning and implementing forest operations to achieve
sustainable forests: Proceedings of papers presented at the joint meeting of
the Council on Forest Engineering and International Union of Forest Research
Organizations. North-Central-Forest-Experiment-Station,
USDA-Forest-Service General-Technical-Report NC-GTR-186. Eds. C.R. Blinn and M.A.
Thompson. 62-72 pp.
Keywords: thinning
tree/stand health
Abstract:
Stand damage studies were conducted on 2 cable thinning operations in
33-year-old Douglas fir (Pseudotsuga menziesii) stands having residual
stockings of 74, 148 and 247 trees/ha in the Oregon Coast Range. The percent of
residual stems damaged increased with decreasing residual density. Average scar
sizes were significant, but at levels lower than cited as major. Observed
thinning damage from helicopter logging was smaller and higher on the stem,
characteristics associated with a lower incidence of decay. Line plots, random
plots, strip transects and blocks on corridors are compared for sampling
damage.
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107. Preston, C.M. and R.H. Newman. 1995. A
long-term effect of N fertilization on the 13C CPMAS NMR of de-ashed soil humin
in second-growth Douglas-fir stand of coastal British Columbia. Geoderma 68(4): 229-241.
Keywords: fertilization
thinning
soil properties
Abstract:
Carbon-13 CPMAS NMR spectroscopy was used to examine long-term effects
of thinning and N fertilization on the humin fraction of soil organic matter in
a second-growth Douglas-fir (Pseudotsuga menziesii) stand in coastal British
Columbia, Canada.
De-ashed OM-enriched humin fractions were prepared from three mineral soil
horizons of four silvicultural treatments using 1.0M HF accompanied by removal
of ferromagnetic iron particles, and a density separation. With some exceptions
a higher proportion of mass was recovered in the denser, light-coloured
fraction, and a higher proportion of C and N in the less-dense, dark fraction.
In all cases, the less-dense fraction was enriched in total C compared to the
original crude humin, and had a more favourable C:Fe
ratio for NMR spectroscopy. The fraction of observable C was 33-37% for 8 of
the samples, but as low as 7.6% for the remaining four. Carbon-13 CPMAS NMR
spectra had typical features for humins (alkyl C, O-alkyl C, di-O-alkyl C, aromatic
C, and carboxyl, ester and amide C). With fertilization, there was a small but
consistent decrease in the ratio of alkyl to O-alkyl C, regardless of horizon
or thinning, indicating a lower extent of decomposition. Carbon-13 subspectra
based on proton spin relaxation time (T1(1H)) were
obtained for one fertilized and one unfertilized sample. Subspectra of the
slowly-relaxing (long T1(1H)) domain were dominated by
long-chain alkyl C. For the fertilized sample, the subspectrum of the
fast-relaxing (short T1(1H)) domain had a higher
proportion of O- and di-O-alkyl C, consistent with results from the normal
CPMAS NMR spectra. Despite the uncertainties introduced by the de-ashing
treatment and the low fraction of observable C, 13C CPMAS NMR showed that fertilization
has a long-term effect which is reflected in this humin fraction.
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108. Ralston, R., J. Buongiorno and J.S. Fried. 2004. Potential yield,
return, and tree diversity of managed, uneven-aged Douglas-fir stands.
Silva-Fennica 38(1): 55-70.
Keywords: thinning
commercial thinning
economics
yield
Abstract:
The effects of different management regimes on uneven-aged Douglas-fir
stands in the Pacific Northwest of the United
States were predicted with a simulation
model. Management alternatives were defined by residual stand structure and cutting
cycle. The residual stand structure was set by basal area-diameter-q-ratio
(BDq) distributions, diameter-limit cuts (assuming concurrent stand
improvement), or the current diameter distribution. Cutting cycles of 10 or 20
years were applied for 200 years. The current diameter distribution was defined
as the average of the uneven-aged Douglas-fir stands sampled in the most recent
Forest Inventory and Analysis conducted in Oregon
and Washington.
Simulation results were compared in terms of financial returns, timber
productivity, species group diversity (hardwoods vs softwoods), size class
diversity, and stand structure. Other things being equal, there was little
difference between 10- and 20-year cutting cycles. The highest financial
returns were obtained with either a 58.4 cm diameter-limit cut, or a BDq
distribution with 8.4 m2 of residual basal area, a 71.1 cm maximum diameter,
and a q-ratio of 1.2. Using the current stand state as the residual
distribution was the best way to obtain high tree size diversity, and high
species group diversity. Several uneven-aged regimes gave net present values
comparable to that obtained by converting the initial, uneven-aged stand to an
even-aged, commercially thinned, plantation.
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109. Riitters, K. and J.D. Brodie. 1984. Implementing optimal thinning
strategies. Forest-Science 30(1): 82-85.
Keywords: thinning
economics
growth
yield
Abstract:
[See FA 41, 3436; 44, 201] A method is described for comparing the
results of optimal thinning analyses based on different management or economic
criteria (such as soil expectation value, forest rent or m.a.i.). Optimal
thinning regimes for Douglas fir and ponderosa pine were calculated using
dynamic programming algorithms based on 2 stand growth simulators. Residual
mean tree volumes were then plotted against stand density at varying time
intervals. On a graph of this kind, the time trajectory of optimal thinning
regimes for even-aged stands is approximately parallel to the line of maximum
size/density.
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110. Rosso, P. and E. Hansen. 1998. Tree vigour and the susceptibility
of Douglas fir to Armillaria root disease. European-Journal-of-Forest-Pathology
28(1): 43-52.
Keywords: fertilization
thinning
pruning
tree/stand protection
growth
tree/stand health
carbon allocation
Abstract:
The effects of thinning, fertilization and pruning on the vigour of
Douglas fir (Pseudotsuga menziesii) and its susceptibility to Armillaria root
disease were investigated in Oregon,
USA. Tree
vigour was defined as the relative capacity for tree growth, expressed as the
above-ground biomass increment per unit of photosynthetic tissue, or growth
efficiency (GE). It has been hypothesized that trees with higher GE can better
resist pathogen attack, and that GE can be used as a predictor of tree
susceptibility to disease. In a previous study, four P. menziesii plantations
were thinned, fertilized and pruned in all combinations, and the effects of
these treatments on tree vigour were measured after 10 years. Root disease was
not a factor in the initial study design, and mortality was ignored until 8
years after the treatments were applied. The results of an earlier study were
utilized and the correlation between Armillaria root disease incidence and the
effects of earlier stand treatments on tree growth was investigated. A. ostoyae
[A. obscura] was the primary cause of mortality in the study area. The disease
incidence of infected subplots ranged from 2 to 20%. A. obscura incidence was
the highest at medium tree density (6.1%), slightly lower on the low density
(5.6%) and lowest on the unthinned plots (3.8%). There were no significant
correlations between disease incidence and previous tree growth. The vigour of
trees that became symptomatic or died by 1993 was not significantly different
from the vigour of trees that remained asymptomatic in 1983-85. On these sites,
in areas of infection, A. obscura was causing mortality of the largest, fastest
growing trees, as well as less vigorous trees. It is concluded that Armillaria
continues to cause mortality, regardless of the growth efficiency or growth
rate of the host.
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111. Sachs, D. and P. Sollins. 1986. Potential effects of management
practices on nitrogen nutrition and long-term productivity of western hemlock
stands. Forest-Ecology-and-Management 17(1): 25-36.
Keywords: thinning
commercial thinning
yield
soil properties
computer modeling
Abstract: The FORCYTE-10 computer model, developed by J.P.
Kimmins and K. Scoullar for Douglas-fir forests in British
Columbia, was modified to simulate growth and
nutrient cycling of coastal western hemlock stands in Oregon.
Initial calibration indicated that predicted yield was extremely sensitive to
the rate of mineralization of soil organic matter (SOM), variation in SOM C/N
ratio with site quality, the soil extractable NO3-/NH4+ ratio, and the
decomposition rate and N mineralization pattern of large and medium-size roots
and woody debris. The predictions suggested that yield and SOM remain stable
under a management system consisting of six successive 90-yr rotations. More
intensive utilization (e.g., shorter rotations, whole-tree harvesting and
commercial thinning) causes depletion of soil and forest floor nitrogen and a
small decline in site productivity in later rotations.
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112. Sachs, D. and J.A. Trofymow. 1991. Testing the performance of
FORCYTE-11 against results from the Shawnigan Lake
thinning and fertilization trials on Douglas-fir. Canadian-Forest-Service,
Pacific and Yukon Region Information-Report BC-X-324. viii
+ 58 p.
Keywords: fertilization
thinning
precommercial thinning
growth
yield
tree physiology
carbon allocation
tree/stand health
computer modeling
Abstract: FORCYTE-11 is an ecosystem-based forest growth
simulation model. Its performance was evaluated with data on stand and tree
biomass, height, stocking (mortality) and foliar assimilation and loss rates
for Douglas fir (Pseudotsuga menziesii) in thinning/fertilizer trials in British Columbia.
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113. Shumway, J.S. and H.N. Chappell. 1995. Preliminary DRIS norms for
coastal Douglas-fir soils in Washington
and Oregon.
Canadian-Journal-of-Forest-Research 25(2): 208-214.
Keywords: fertilization
thinning
growth
soil properties
Abstract:
The Diagnosis and Recommendation Integrated System (DRIS) has been
used successfully to evaluate interactions between nutrients and fertilizer
response and for diagnosing nutrient deficiency in agricultural crops. This
study used soil tests to develop DRIS norms and evaluate their effectiveness in
coastal Douglas fir (Pseudotsuga menziesii) forests. DRIS norms for nitrogen,
phosphorus, potassium, and calcium were developed using soil test and site
index data from 72 soil series that commonly support Douglas fir in western Washington. The norms were
tested using soil test and stand basal area growth response data from 20
thinned and 30 unthinned N fertilizer test sites in coastal Washington and Oregon. Response to urea fertilizer in thinned
stands averaged 34% and 43% for 224 and 448 kg N.ha-1, respectively, when N was
identified as the most limiting nutrient. When N was not the most limiting
nutrient, N response averaged 8% and 10% for 224 and 448 kg N.ha-1,
respectively. Results were similar in unthinned stands and thinned stands,
although response to fertilizer appeared to be slightly less in unthinned
stands when N was the most limiting nutrient. DRIS correctly classified 25 of
the 33 sites (76%) where N fertilizer increased growth by more than 15%. More importantly,
13 of the 17 (76%) sites that responded by less than 15% were correctly
identified by DRIS. The results clearly indicate that N fertilizer response is
dependent on the interactions (balance) between soil nutrients at a given site.
Future soil diagnostic work needs to focus on techniques, like DRIS, that
provide an assessment of these interactions.
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114. Smith, S.H. and J.F. Bell. 1983. Using competitive stress index
to estimate diameter growth for thinned Douglas-fir stands. Forest-Science
29(3): 491-499.
Keywords: thinning
growth
Abstract:
A set of linear growth equations was developed using initial diam.
(d.b.h.), initial competitive stress index (CSI, based on area of overlap of
growing space), and change in CSI due to thinning as independent variables to
predict periodic diam. growth response for 3- and 4-yr growth periods. CSI
values were calculated from data collected in a naturally developed, pure,
even-aged stand in Oregon
[see FA 34, 2219]. Study plots were established in 1963, when the stand was 20
yr old, and thinned at varying intensities in 1963, 1966, 1970 and 1973. The
data was divided into 2 periods: 1966-70 and 1970-73. Functions including all 3
independent variables accounted for the greatest variation in periodic diam.
increment for both growth periods. Including transformations of initial CSI and
change in CSI in the model provided significant improvements over a model based
only on functions of initial d.b.h.
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115. Sonne, E., E. Turnblom, D. Briggs and G. Becker. 2004. Log and
lumber grades and value from a Douglas-fir stand 20 years after thinning and
biosolids fertilization. Western-Journal-of-Applied-Forestry 19(1): 34-41.
Keywords: fertilization
thinning
economics
yield
wood quality
Abstract:
Three replications of four treatments: biosolids fertilizer
application, thinning, thinning plus biosolids fertilizer application, and
untreated control were established in 1977 in a dense, low site, 55-year-old
Douglas-fir (Pseudotsuga menziesii) stand in western Washington, USA. In 1998,
12 trees from each treatment were harvested, bucked into logs, and sawn into
visually graded lumber. Taking into account effects of treatments on stand
yield and log grades, biosolid fertilizer application only, thinning only, and
thinning combined with biosolids increased log value/ac by $1142 (19%), $3642
(62%), and $9969 (155%), respectively, over the untreated control. When
treatment effects were viewed in terms of changes in lumber yield and quality,
per acre gains over the control were $2107 (26%), $5683 (70%), and $10 708
(132%), respectively. Willingness to pay analysis indicates that if the
landowner intends to manage the stand to a rotation of approximately 75 years,
each of the treatments, and especially the combination of thinning and applying
biosolids, appears to be financially attractive at both 5 and 9% interest
rates. However, if the rotation had been set at 55 years, only the
thinning/biosolids combination at 5% interest rate would entice management to
delay immediate harvest.
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116. Stegemoeller, K.A. and H.N. Chappell. 1990. Growth response of
unthinned and thinned Douglas-fir stands to single and multiple applications of
nitrogen. Canadian-Journal-of-Forest-Research 20(3): 343-349.
Keywords: fertilization
thinning
growth
Abstract:
Basal area and volume growth response of unthinned and thinned Douglas
fir (Pseudotsuga menziesii) stands to single and multiple applications of N
fertilizer (as urea) were estimated for eight 2-yr periods in second-growth
stands in Washington and Oregon.
Response estimates, as differences between growth rates on fertilized and
control plots after adjusting for initial volume (or basal area), and trends,
were analysed on a regional scale. Average responses to the initial
fertilization and to both the second and third fertilizer applications, 8 and
12 yr later, were statistically significant (P <0.05). In thinned stands,
average duration of response to the initial treatment was approximately 8 yr;
unthinned stands continued to show significant volume growth response through
14 yr although basal area growth response decreased to nonsignificant levels
between years 10 and 12. In both cases, the response to refertilization, while
significant, was smaller than the response to the initial fertilization. N
applied after the 8th yr and a refertilization after the 12th, on one initially
untreated plot at each site, also produced significant average growth
responses.
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117. Stegemoeller, K.A. and H.N. Chappell. 1991. Effects of
fertilization and thinning on 8-year growth responses of second-growth Douglas
fir stands. Canadian-Journal-of-Forest-Research 21(4): 516-521.
Keywords: fertilization
thinning
growth
Abstract:
An evaluation is presented of a regional research project on basal area and
volume increment responses to fertilizer (N) and fertilizer with thinning
treatments of Pseudotsuga menziesii in W. Washington and
Oregon for four 2-year
measurement periods. Fertilization generally increased both basal area and
volume growth for at least 8 years. Thinning tended to have an even greater
effect than fertilization on basal area and volume growth on an individual-tree
basis. Overall, however, the removal of growing stock by thinning caused volume
growth to be less than that of the control. The magnitude and duration of this
negative response was dependent on the level of thinning and on site quality. A
significant positive interaction between fertilization and thinning exists. The
combined treatment resulted in the greatest absolute basal area and volume
increments, and the response became greater than that to fertilizer alone in
the 3rd and 4th years, and remained so for at least 8 years.
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118. Stinson, S.D.
1999. 50 years of low thinning in second growth Douglas-fir. Forestry-Chronicle
75(3): 401-405.
Keywords: thinning
growth
yield
wood quality
Abstract:
Results are presented from four of the Port Blakely XT series of
thinning trials, established during 1948-58 in naturally regenerated Douglas
fir [Pseudotsuga menziesii] stands in western Washington.
Three trials were designed to evaluate the effects of repeated low thinning and
extended rotations, while the fourth compared the effects of different levels
of removal on standing volume and wood quality. Periodic and mean annual
increment trends were examined in all trials. Results indicated the extension
of culmination of mean annual increment in response to low thinning, combined with
extended rotations. Thinned plots in 2 trials had increased stem size and total
harvested volume. Extended rotations and low thinning increased the quantity of
structural log grades when compared with stands harvested on shorter rotations.
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119. Stone, M. 1993. An economic evaluation of
commercial thinning Douglas-fir in the coastal region of British Columbia.
BC Ministry of Forests FRDA-Working-Paper WP-6-002. x + 146 p.
Keywords: thinning
commercial thinning
economics
growth
yield
Abstract:
The economic evaluation of commercial thinning of Douglas fir [Pseudotsuga
menziesii] in the coastal region of British Columbia,
includes an estimation of the economic effects of the thinning on the final
harvest. This was done by simulating the growth and yield impacts of a
commercial thinning, estimating the potential costs and revenues derived from
the thinning and the final harvest, and determining the net present value of
the full impacts of commercial thinning.
Non-OSU
Link
120. Strand, R.F. and D.S. DeBell. 1981. Growth
response to fertilization in relation to stocking levels of Douglas-fir. In
Proceedings: Forest Fertilization Conference, University
of Washington, Seattle, Washington, USA.
Eds. S.P. Gessel, R.M. Kenady and W.A. Atkinson. pp.
102-106.
Keywords: planting
operations
fertilization
thinning
growth
Abstract:
Growing stock levels affect the response of Douglas-fir stands to
applications of nitrogen fertilizer. Response is maximum
at intermediate stocking levels, and is less at higher or lower levels of stand
density. Nitrogen fertilization accelerates growth and therefore increases the
rate of buildup of stand density. Thinnings will be required to reduce stocking
to appropriate levels if good responses to repeated nitrogen applications
throughout a rotation are to be obtained.
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121. Tait, D.E. 1988. The dynamics of stand development: a general
stand model applied to Douglas-fir. Canadian-Journal-of-Forest-Research 18(6):
696-702.
Keywords: planting
operations
thinning
growth
tree/stand health
Abstract:
A linked pair of hypotheses are developed that represent causal explanations
for plant growth and stand mortality for an even-aged stand. The pair of
dynamic equations lead to a four-parameter Douglas fir
simulation model that relates the development of stand volume and density to
site quality, initial stocking density and alternative thinning regimes. The
mortality hypothesis, a dynamic hypothesis related to stand density and stand
growth, generates the -superscript 3/2 power law as an equilibrium solution.
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122. Tappeiner, J.C., J.F. Bell and J.D. Brodie. 1982. Response of
young Douglas-fir to 16 years of intensive thinning.
Forest-Research-Laboratory,-Oregon-State-University
Keywords: thinning
growth
yield
tree/stand health
economics
Abstract:
The report of the thinning study in the Oregon
Coast Range
includes a financial analysis of representative thinning regimes.
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123. Taylor, A.M., B.L.
Gartner and J.J. Morrell. 2003. Co-incident variations in growth rate and
heartwood extractive concentration in Douglas-fir.
Forest-Ecology-and-Management 186(1/3): 257-260.
Keywords: thinning
growth
wood quality
Abstract:
Extractives can have a major impact on the properties of heartwood;
however, our understanding of the process of heartwood formation and
extractives production is limited and there are few data on how environment affects
heartwood extractive content. This study assessed the relationship between
growth ring width and extractive content of heartwood in Douglas-fir
(Pseudotsuga menziesii [Mirbel] Franco) trees. The radial growth rates of the
sampled trees were variable over their 53-61 years, in part, because of recent
stand thinning treatment. The year that each heartwood increment was formed was
estimated by assuming that the trees maintained the same number of growth rings
of sapwood in the past as they had at the time of sampling. Growth ring width
increased after the recent thinning and there was an associated increase in the
extractive content of the heartwood estimated to have been formed at the same
time. In addition, there appeared to be a rough correlation between growth ring
width and extractive content in the time before the thinning. These results
suggest that silvicultural treatments that affect growth rate may affect wood
durability in Douglas-fir.
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124. Tesch, S.D.,
G.M. Filip, S.A. Fitzgerald and D.D. Marshall. 1994. Silvicultural treatments
for enhancing tree value, vigor, and growth in 70- to 120-year-old stands
dominated by noble fir on the Warm Springs Indian Reservation: a synthesis of
the literature. Forest Research Laboratory, College of Forestry,
Oregon State University. iii + 21 p.
Keywords: fertilization
thinning
pruning
tree/stand protection
growth
yield
tree/stand health
Abstract:
The Warm Springs Indian Reservation, Oregon,
apparently contains some 30 000 acres of naturally regenerated, largely
unmanaged stands of 70- to 120-year-old mixed conifer forest dominated by noble
fir (Abies procera), with Douglas-fir [Pseudotsuga menziesii], and some Pacific
silver fir [Abies amabilis] and western hemlock [Tsuga heterophylla]. The
synthesis focuses on growth and yield, thinning, pruning, fertilizer treatment,
disease, minimizing stand damage during thinning, and insect pests.
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125. Thies, W.G. and R.N. Sturrock. 1995. Laminated root rot in Western North America. Pacific
Northwest Research Station, USDA Forest
Service General Technical Report GTR-PNW-349. iv
+ 32 pp. p.
Keywords: planting
operations
site
preparation
mechanical
preparation
fertilization
thinning
tree/stand
protection
tree/stand
health
Abstract:
Laminated root rot, caused by Phellinus weirii, is a serious root disease
affecting Douglas fir (Pseudotsuga menziesii) and other commercially important
species of conifers in northwestern North America. This
report gives an overview of the disease as it occurs in the Pacific
Northwest in Canada
and the USA.
Information on recognizing crown symptoms and signs of the disease is
presented. The disease cycle of laminated root rot, from initiation to
intensification and distribution within infected stands, is described. Finally,
disease management strategies during stand development and at stand regeneration
are discussed. Features on the nomenclature of the fungus and on its management
by silvicultural and mechanical approaches also are included.
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126. Thomson, A.J. and H.J. Barclay. 1984. Effects of thinning and
urea fertilization on the distribution of area increment along the boles of
Douglas-fir at Shawnigan Lake,
British Columbia.
Canadian-Journal-of-Forest-Research 14(6): 879-884.
Keywords: fertilization
thinning
tree morphology
growth
Abstract:
Assessments were made using radial growth measurements made 6 and 9 yr
after treatment. Within treatments, av. area increment per tree was linearly
related to d.b.h. and this relation was used to evaluate the effects of
treatment on growth rate. Fertilizing had the greatest effect on av. area
increment, and for a particular fertilization regime, thinning increased the
response. Thinning modified the distribution of growth over the bole of all
trees and increased butt flare, especially in smaller trees. The effect
declined from the 4- to 6-yr measurement period to the 7- to 9-yr measurement
period. Fertilizing had no consistent effect on growth distribution. The regression
methods used in this study provided a more sensitive measure of form changes
than previous methods, were independent of size distribution, and facilitated
extrapolations and evaluation of temporal trends.
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127. Trofymow, J.A., H.J. Barclay and K.M. McCullough. 1991. Annual
rates and elemental concentrations of litter fall in thinned and fertilized
Douglas-fir. Canadian-Journal-of-Forest-Research 21(11): 1601-1615.
Keywords: fertilization
thinning
soil properties
Abstract:
Overstorey litterfall (primarily needles) was collected for 15 years
(1972-86) within control and treated plots in a Douglas fir (Pseudotsuga
menziesii) stand near Shawnigan Lake, British
Columbia. Treated plots were thinned or fertilized,
or both. Thinned plots had two-thirds of their basal area removed; fertilized
plots were treated with 448 kg N/ha of either urea or ammonium nitrate, and the fertilized plots were refertilized at the
same rate 9 years later. The annual rate of litterfall in control plots
averaged 1890 kg/ha. In control plots, significant yearly variations were
observed in litterfall mass and concentrations of K, Mg, and Ca but not N or P.
Thinning decreased rates of litterfall by 80%, but rates returned to
control-plot levels after 13-15 years in unfertilized plots and after 8-10
years in fertilized plots. Fertilizer treatment without thinning depressed
litterfall in the year of treatment but increased the rate by 20-80% in
subsequent years. Litterfall N concentrations increased by 40-80% the year of
fertilizer treatment and then began decreasing 3-6 years later. Nitrogen
fertilization reduced litterfall P, K and Mg concentrations for 8, 4 and 1
year(s), respectively, following fertilizer treatment. The effects were greater
in ammonium nitrate plots than in urea plots. Rates of litterfall correlated
poorly with stand density but well with basal area and stemwood increment.
Correlations with the latter two variables varied with time and treatment.
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128. Velazquez-Martinez, A. and D.A. Perry. 1997. Factors influencing
the availability of nitrogen in thinned and unthinned Douglas-fir stands in the
central Oregon Cascades. Forest-Ecology-and-Management 93(3): 195-203.
Keywords: fertilization
thinning
soil properties
Abstract:
Soil N mineralized during 7-day anaerobic incubation at 40 degrees C (available
N) was compared at 2 soil depths and correlated with soil and site factors in
Douglas fir [Pseudotsuga menziesii] stands with different combinations of
thinning and multinutrient fertilizing. Available N expressed either on an area
basis (kg ha-1) or on a concentration basis (mg kg-1) at the 2 depths did not
vary significantly by stocking density, treatment, or density-treatment
interaction. There was a significant difference between the soil depths,
averaging 39 mg kg-1 at 0-20 cm depth, and 20 mg kg-1 at 20-40 cm depth.
Available N was positively correlated with total soil N, exchangeable Ca, and
adjusted aspect (the former 2 factors accounting for 46% of the total
variation), and negatively with rock content and slope steepness. Stand density
had no effect.
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129. Velazquez-Martinez, A., D.A. Perry and T.E. Bell. 1992. Response
of aboveground biomass increment, growth efficiency, and foliar nutrients to
thinning, fertilization, and pruning in young Douglas-fir plantations in the
central Oregon Cascades. Canadian-Journal-of-Forest-Research 22(9): 1278-1289.
Keywords: fertilization
thinning
pruning
growth
carbon allocation
tree physiology
tree morphology
Abstract:
The effect of thinning and silvicultural practices (multinutrient fertilization
and/or pruning) on total aboveground biomass increment and growth efficiency
was studied over three consecutive 2-year periods (1981-1987) in young Douglas
fir (Pseudotsuga menziesii) plantations in the central Oregon Cascades.
Plantations were 21-27 yr old in 1987. Plots were heavily thinned (leaving 300
trees/ha), moderately thinned (leaving 604 trees/ha) or left unthinned (leaving
3459 trees/ha) in 1981. Fertilizer (N, P, K, Ca, S and Fe) was applied with slow-release
tabs. Net above-ground biomass annual increment over the 6-year period averaged
14.5, 7.8, and 5.5 t/ha for the high-, medium-, and low-density plots,
respectively. Growth efficiency, after dropping sharply between leaf area
indexes (LAI) of 1 and 6 msuperscript 2/msuperscript 2, remained relatively
constant up to the highest measured LAI of 17. Consequently, above-ground
biomass increment continued to increase at LAIs well above that at which the
Beer-Lambert law predicts maximum light should be absorbed. Foliage analyses
indicated that thinning improved N, K and Mg nutrition and increased the
translocation of K from 1-yr-old foliage to support new growth. However,
fertilizer application increased foliar N and P contents only when coupled with
pruning, suggesting that trees favour total leaf area over individual needle
nutrition. Indications of K and Mg limitations in this study are supported by
other recent studies of Douglas fir.
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130. Williamson, R.L. 1982a. Applicability of four
regional volume tables for estimating growth response to thinning in
Douglas-fir. Pacific-Northwest-Forest-and-Range-Experiment-Station,
USDA-Forest-Service Research-Paper PNW-RP-295. 10 p.
Keywords: thinning
commercial thinning
growth
Abstract:
A 110-yr-old stand in Washington
was given light or heavy thinning or left unthinned in 1952 and 1971. Stem
sections were taken from trees removed in 1971 and analysed to show volume
growth for the 19 yr before and 19 yr after the 1952 thinning. Estimates of
volume growth for the same stand were also made from 4 volume tables and the
results compared. The agreement between volume table estimates and the stem
analysis results was within 10%, and was unaffected by thinning severity.
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131. Williamson, R.L. 1982b. Response to commercial
thinning in a 110-yr-old Douglas-fir stand. Pacific-Northwest-Forest-and-Range-Experiment-Station,
USDA-Forest-Service Research-Paper PNW-RP-296. i + 16
p.
Keywords: thinning
commercial thinning
growth
tree/stand health
Abstract:
[See FA 28, 584] A stand in Washington
was thinned in 1952 to 75 or 50% of normal b.a. After 19 yr the plots were
remeasured and thinned again and stem analyses made for felled trees. Overall
growth was similar in thinned and control plots, although mortality was 3-5x higher on control plots. The growth response relative to
control trees was significantly greater for suppressed trees in the heavily
thinned plots.
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132. Williamson, R.L. and R.O. Curtis. 1984. Levels-of-growing-stock
cooperative study in Douglas-fir. Report No. 7 - Preliminary
results, Stampede Creek, and some comparisons with Iron Creek and Hoskins.
Pacific-Northwest-Forest-and-Range-Experiment-Station,-USDA-Forest-Service Research-Paper
PNW-RP-323. v + 42 p.
Keywords: thinning
commercial thinning
growth
Abstract:
[See FA 43, 3890, 6692] A further report in a series
on 9 study areas in Canada
and the USA.
Results are summarized for a 43-yr-old stand in SW Oregon,
which was 'calibration thinned' in 1968 (aged 33 yr) and thinned again to
retain 10-70% of the b.a. increment of the untreated
control plot at age 38 yr. Recommendations for desirable density are given.
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133. Wilson, J. 2004. Vulnerability to wind damage in managed
landscapes of the coastal Pacific Northwest.
Forest-Ecology-and-Management 191(1/3): 341-351.
Keywords: planting
operations
thinning
tree/stand protection
computer modeling
tree/stand health
Abstract:
Managed forested landscapes in the coastal Pacific
Northwest follow a pattern of transition from dominance by
naturally regenerated second growth to dominance by planted stands. This
transition should have dramatic influence on many characteristics of these
landscapes and the larger region, including susceptibility to wind damage. In
this paper, inventory and spatial information from an example landscape are
integrated using the Landscape Management System to produce alternative
management scenarios and evaluate the projections using a wind damage
vulnerability rating system. Planted Douglas-fir stands tend to develop higher
height to diameter ratios in the dominant trees, are thinned more often, and
tend to have more exposed windward edges; characteristics which increase
susceptibility to wind damage. In this analysis, the increasing vulnerability
factors are mostly compensated for by the reduced rotation lengths expected in
the plantations. The pattern of transition in managed landscapes generates an
associated pattern of vulnerability to wind damage. Homogeneously and
heterogeneously aged landscapes have distinct patterns of vulnerability. These
differences could be harnessed to enhance the particular goals associated with
managing individual ownerships.
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134. Wilson, J.S. and P.J.
Baker. 2001. Flexibility in forest management: managing uncertainty in
Douglas-fir forests of the Pacific Northwest.
Forest-Ecology-and-Management 145(3): 219-227.
Keywords: planting
operations
thinning
yield
tree morphology
economics
tree/stand health
Abstract:
Long planning horizons generate substantial uncertainty in forest
management, making management flexibility, the ability to choose between
multiple options or opportunities, a desirable attribute of managed forests.
Flexibility in forest management reflects both the relative rigidity of
intervention requirements and the potential range of development pathways for a
stand. The wind stability of Pacific Northwest
Douglas-fir (Pseudotsuga menziesii) plantations is used to demonstrate the
concept of management flexibility. Dense Douglas-fir plantations develop high
height to diameter ratios in the dominant trees making them unstable and prone
to wind damage. The management of these plantations is inflexible, because
without early and timely thinning, the stands do not contain stable trees that
could be expected to survive long rotations or late thinnings. A combination of
reduced planting densities and site-specific management reduces both the
necessity and rigidity of intervention requirements (e.g., thinning) and
expands the number of potential developmental pathways for these stands. The
cost of greater management flexibility is reduced efficiency of wood volume
production; however, greater adaptability to changing markets, labour
conditions, and management objectives may be more important for many forest
owners. While this approach to management is complex, it frees owners and
managers from rigid management requirements and allows for a wider range of
future stand conditions.
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135. Wilson, J.S. and C.D.
Oliver. 2000. Stability and density management in Douglas-fir plantations.
Canadian-Journal-of-Forest-Research 30(6): 910-920.
Keywords: planting
operations
thinning
tree/stand protection
tree morphology
tree/stand health
Abstract:
Limited tree size variation in Douglas fir (Pseudotsuga menziesii)
plantations in coastal Oregon, Washington,
and British Columbia makes them
susceptible to developing high height to diameter ratios (H/D) in the dominant
trees. The H/D of a tree is a relative measure of stability under wind and snow
loads. Experimental plot data from three large studies were used to evaluate
the impact of initial planting densities and thinning on plantation H/D values.
The H/D predictions from the experimental plot data match spacing trial results
closely but are substantially different from distance-independent growth model
predictions. The results suggest that plantation H/D values can be lowered and
stability promoted through reduced planting densities or early thinning;
however, later thinnings may not be effective in promoting stability, since
they do not appear to lower H/D values. Higher initial planting densities
shorten the time period during which thinning can be expected to effectively
lower future H/D values. Time-sensitive thinning requirements in dense
plantations make their management inflexible. The flexibility with which a
stand can be managed describes the rigidity of intervention requirements and/or
potential range of stand development pathways.
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136. Wimberly, M.C. and B.B. Bare. 1996. Distance-dependent and
distance-independent models of Douglas-fir and western hemlock basal area
growth following silvicultural treatment. Forest-Ecology-and-Management
89(1/3): 1-11.
Keywords: fertilization
thinning
growth
Abstract:
Distance-independent and distance-dependent individual-tree basal area
growth equations for Douglas fir (Pseudotsuga menziesii) and western hemlock
(Tsuga heterophylla) growth following thinning and fertilizer treatments were
developed using regression analysis. Data came from an even-aged, naturally
regenerated, mixed species stand near Jordan River,
SW Vancouver Island, Canada. Distance-independent models included only
non-spatial competition and thinning indices, while distance-dependent models
included both spatial and non-spatial indices. The distance-independent models
with the highest adjusted multiple coefficient of determination (adjusted
Rsuperscript 2) for both species included diameter at breast height, crown
class, percent basal area removed in thinning, plot basal area greater than the
subject tree and stand age as independent variables. The distance-dependent
models with the highest adjusted Rsuperscript 2 included all of these variables
in addition to a variant of the area potentially available index, which is
based on the spatial tessellation of the point pattern of trees in the stand.
Addition of this spatial index produced only a small (<.01) increase in
adjusted Rsuperscript 2 for models of both species. The relatively small amount
of increase was due to three factors: thinning resulted in an even distribution
of growing space among residual trees; tree size explained much of the
variation in local competitive stress; and the competitive neighbourhood of
individual trees was large relative to sample plot size. The results suggest
that the additional effort and expense required to obtain spatially referenced
stand data for developing empirical forest growth models in similar stands is
not justified.
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